bench: replace CreateMockableWalletDatabase with MakeInMemoryWalletDatabase #35705

Benchmarks don't need mock-specific behaviour (overridden Filename(), Format(), or the exposed batch-level WriteKey()). Replace CreateMockableWalletDatabase() with MakeInMemoryWalletDatabase() across all 6 call sites in src/bench/ (5 files - 4 wallet bench files + 1 in coin_selection), using the same in-memory SQLite path that production code uses.

wallet_migration.cpp is excluded: it calls GetOrCreateLegacyDataSPKM() which asserts Format() == "sqlite-mock", a deliberate signal that allows legacy SPKM setup in test/bench contexts. MockableSQLiteDatabase is still correct there.

For coin_selection.cpp, which had no other dependencies on wallet/test/util.h, the include is switched to <wallet/sqlite.h>. The remaining 4 files retain wallet/test/util.h for other utilities but also add an explicit <wallet/sqlite.h> include as required by IWYU.

Follow-up suggested in #35655.

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Code Coverage & Benchmarks

For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/35705.

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🚧 At least one of the CI tasks failed. _{Task iwyu: https://github.com/bitcoin/bitcoin/actions/runs/29221617518/job/86727716744} _{LLM reason (✨ experimental): CI failed because IWYU reported missing/incorrect #include dependencies (triggering “Failure generated from IWYU”).}

<details><summary>Hints</summary>

Try to run the tests locally, according to the documentation. However, a CI failure may still happen due to a number of reasons, for example:

• Possibly due to a silent merge conflict (the changes in this pull request being incompatible with the current code in the target branch). If so, make sure to rebase on the latest commit of the target branch.

• A sanitizer issue, which can only be found by compiling with the sanitizer and running the affected test.

• An intermittent issue.

Leave a comment here, if you need help tracking down a confusing failure.

</details>

ACK 7508ac319d992eb0a731a7b2e879bcad5859c3c4

ACK 7508ac319d992eb0a731a7b2e879bcad5859c3c4

PR removes an unnecessary test-only indirection, after #35655. LGTM

Code review, build and checked if this has any consequences for benchmarking (all within variance)

<details>

This PR:

|        ns/selection |         selection/s |    err% |     total | benchmark
|--------------------:|--------------------:|--------:|----------:|:----------
|        4,188,525.00 |              238.75 |    0.1% |      0.46 | `CoinSelection`

|               ns/op |                op/s |    err% |     total | benchmark
|--------------------:|--------------------:|--------:|----------:|:----------
|       35,623,583.00 |               28.07 |    0.0% |      0.39 | `WalletAvailableCoins`
|            3,083.00 |          324,359.39 |    1.3% |      0.00 | `WalletBalanceClean`
|            3,125.00 |          320,000.00 |    0.0% |      0.00 | `WalletBalanceDirty`
|               41.00 |       24,390,243.90 |    2.4% |      0.00 | `WalletBalanceWatch`
|          807,584.00 |            1,238.26 |    0.4% |      0.01 | `WalletCreateTxUseOnlyPresetInputs`
|       21,648,458.00 |               46.19 |    1.8% |      0.24 | `WalletCreateTxUsePresetInputsAndCoinSelection`

|              ns/key |               key/s |    err% |     total | benchmark
|--------------------:|--------------------:|--------:|----------:|:----------
|          199,289.15 |            5,017.83 |    0.3% |      4.39 | `WalletEncryptDescriptors`

|               ns/op |                op/s |    err% |     total | benchmark
|--------------------:|--------------------:|--------:|----------:|:----------
|               37.46 |       26,692,554.06 |    0.2% |      0.01 | `WalletIsMineDescriptors`
|               37.86 |       26,411,598.60 |    0.3% |      0.01 | `WalletIsMineMigratedDescriptors`

Master:

|        ns/selection |         selection/s |    err% |     total | benchmark
|--------------------:|--------------------:|--------:|----------:|:----------
|        4,128,975.00 |              242.19 |    0.2% |      0.45 | `CoinSelection`

|               ns/op |                op/s |    err% |     total | benchmark
|--------------------:|--------------------:|--------:|----------:|:----------
|       35,544,333.00 |               28.13 |    0.1% |      0.39 | `WalletAvailableCoins`
|            3,083.00 |          324,359.39 |    1.3% |      0.00 | `WalletBalanceClean`
|            3,166.00 |          315,855.97 |    1.3% |      0.00 | `WalletBalanceDirty`
|               41.00 |       24,390,243.90 |    2.4% |      0.00 | `WalletBalanceWatch`
|          729,834.00 |            1,370.17 |    0.3% |      0.01 | `WalletCreateTxUseOnlyPresetInputs`
|       21,700,541.00 |               46.08 |    1.7% |      0.24 | `WalletCreateTxUsePresetInputsAndCoinSelection`

|              ns/key |               key/s |    err% |     total | benchmark
|--------------------:|--------------------:|--------:|----------:|:----------
|          198,431.87 |            5,039.51 |    0.2% |      4.37 | `WalletEncryptDescriptors`

|               ns/op |                op/s |    err% |     total | benchmark
|--------------------:|--------------------:|--------:|----------:|:----------
|               36.81 |       27,168,938.22 |    0.1% |      0.01 | `WalletIsMineDescriptors`
|               37.38 |       26,750,031.75 |    0.4% |      0.01 | `WalletIsMineMigratedDescriptors`

</details>