Drop support for bazel5; switch to all bzlmod. #4793

Job	Run time
KytheXrefs	0s
ClangTidy	6m 44s
KytheVerification	0s
x86_64 test	5m 51s
MacOsBuild	5m 59s
arm64 test	7m 3s
PrepareVSPlugin	2m 37s
RunBantBuildCleaner	3m 14s
x86_64 test-clang	12m 33s
arm64 test-clang	6m 30s
VerifyFormatting	25s
WindowsBuild	31m 46s
x86_64 test-nortti	5m 48s
x86_64 test-c++20	5m 48s
x86_64 test-c++23	5m 49s
x86_64 smoke-test	12m 7s
arm64 smoke-test	14m 14s
x86_64 asan	7m 14s
x86_64 asan-clang	13m 23s
x86_64 compile	6m 26s
arm64 compile	5m 55s
x86_64 compile-clang	5m 3s
arm64 compile-clang	6m 5s
x86_64 compile-static	5m 36s
arm64 compile-static	6m 0s
x86_64 compile-static-clang	5m 57s
arm64 compile-static-clang	5m 57s
x86_64 clean	6m 25s
arm64 clean	6m 56s
Build and deploy GitHub pages	11s
📦 Release	0s
	3h 27m 36s

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