[PWGCF] Fix MC processing, remove tmp histograms from registry

[EmilGorm]

• Fix to MC reco and MC gen processing for radial and elliptic flow-spectra correlations
• Temporary histograms for tracking EbyE spectra have been removed from the histogram registry to remove clutter in the output
• Some changes to enum names to conform to coding guidellines
• Proper use of subevent-averaged mean pt for v0

[github-actions]

O2 linter results: ❌ 0 errors, ⚠️ 0 warnings, 🔕 0 disabled

[vkucera]

Why don't you fix the magic numbers and names?

[alibuild]

Error while checking build/O2Physics/staging for 05b98e2 at 2026-05-07 00:09:

## sw/BUILD/O2Physics-latest/log
CMake Error at /sw/slc9_x86-64/CMake/v4.1.4-2/share/cmake-4.1/Modules/CMakeTestCCompiler.cmake:67 (message):
    2026-05-07T00:09:54.066+0200 [70:140425928646272] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "ActionCache.GetActionResult()", last gRPC error was [14: failed to connect to all addresses; last error: UNKNOWN: ipv4:127.0.0.1:8085: Failed to connect to remote host: Connection refused]
    2026-05-07T00:09:54.066+0200 [70:140425928646272] [executioncontext.cpp:544] [ERROR] Error while querying action cache at "http://localhost:8085": 14: failed to connect to all addresses; last error: UNKNOWN: ipv4:127.0.0.1:8085: Failed to connect to remote host: Connection refused
    2026-05-07T00:09:54.069+0200 [70:140425928646272] [buildboxcommon_grpcretrier.cpp:177] [ERROR] Retry limit (0) exceeded for "FindMissingBlobs()", last gRPC error was [14: failed to connect to all addresses; last error: UNKNOWN: ipv4:127.0.0.1:8085: Failed to connect to remote host: Connection refused]
    2026-05-07T00:09:54.069+0200 [70:140425928646272] [executioncontext.cpp:908] [ERROR] Error while uploading resources to CAS at "http://localhost:8085": 14: failed to connect to all addresses; last error: UNKNOWN: ipv4:127.0.0.1:8085: Failed to connect to remote host: Connection refused
    ninja: build stopped: subcommand failed.

Full log here.