test: use monotonic clock for durations in test framework and http_interface #36731

Replace time.time() used to measure durations by time.monotonic() in test framework and http_interface.

This helps preventing future clock jump flakiness (same class of bug as #36529) on tests and fix:

faketime --exclude-monotonic -f "+0 x0.5" build/test/functional/feature_torcontrol.py
faketime --exclude-monotonic -f "+0 x0.1" build/test/functional/interface_http.py

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External sites

• Code coverage & benchmarks: https://corecheck.dev/bitcoin/bitcoin/pulls/36731
• Ralph review <img src=https://review.fish.foo/assets/bitcoin/bitcoin/36731.png alt="Ralph review status"> https://git.fish.foo/bitcoin/bitcoin/pulls/36731#author-ralph

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Concept ACK

read my mind https://github.com/nervana21/bitcoin/tree/test-monotonic-wait-deadlines

tACK a7d3a4297321274ced64294e0bbd3252167e8879

I used a method similar to OP's and got the same results.

Could we also fix interface_ipc_mining? I think it has the same class of bug.

review ACK a7d3a4297321274ced64294e0bbd3252167e8879 🕐

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ACK a7d3a4297321274ced64294e0bbd3252167e8879