Add TLogGenerationUnavailable trace event#12846

tclinkenbeard-oai wants to merge 3 commits intoapple:mainapple/foundationdb:mainfrom

tclinkenbeard-oai:dev/tclinkenbeard/tlog-gen-unavailable-loggingtclinkenbeard-oai/foundationdb:dev/tclinkenbeard/tlog-gen-unavailable-loggingCopy head branch name to clipboard