After using Threadpool for HTTp server in PR 33689, the previously documented HTTP worker thread names are outdated. This commit makes the corresponding changes to document new names for the HTTP pool threads. Below is the output from the thead list command after attaching lldb to bitcoind.
0thread [#3](/bitcoin-bitcoin/3/): tid = 0xfe551, 0x00007ff80e3536f6 libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'b-http_pool_0'
1thread [#4](/bitcoin-bitcoin/4/): tid = 0xfe552, 0x00007ff80e3536f6 libsystem_kernel.dylib`__psynch_cvwait + 10, name = 'b-http_pool_1'