CXX-3194 Migrate from macos-1100 to macos-14-arm64

[eramongodb]

Similar to mongodb/mongo-c-driver#1791, motivated by DEVPROD-21. Verified by this patch.

MongoDB Server 5.0 tasks remain on macos-14 (Intel) due to lack of availability on macos-14-arm64.

Also an attempt to avoid spurious Clang internal compiler errors as observed in this patch.

clang: error: unable to execute command: Segmentation fault: 11
clang: error: clang frontend command failed due to signal (use -v to see invocation)
Apple clang version 12.0.0 (clang-1200.0.32.29)
Target: x86_64-apple-darwin20.6.0
Thread model: posix

The addition of -Wno-aligned-mismatch was necessary to address compilation errors similar to those currently being silenced by -Wno-aligned-new for GCC (see "Extra Alignment" in PR description of #1244).

[eramongodb]

The macos-11 distro appears to have observable differences from the macos-1100 distro concerning the presence of a thread library as (not) detected by CMake's FindThreads module (despite both using macos-11-amd64 hosts). Reverted to macos-1100 for now; a followup PR will complete the transition to macos-11-arm64 once DEVPROD-13222 is resolved.