Merge pull request #63680 from mikeash/lsan-limit-link-jobs-5.8

[5.8][Build] Limit Ubuntu 18.04 LSAN CI to 12 link jobs

Author: mikeash

utils/build-presets.ini

@@ -1197,6 +1197,9 @@ reconfigure
 [preset: buildbot_incremental_linux,lsan,tools=RDA,stdlib=DA,test=no]
 build-subdir=buildbot_incremental_lsan
 
+llvm-cmake-options=-DLLVM_PARALLEL_LINK_JOBS=12
+swift-cmake-options=-DSWIFT_PARALLEL_LINK_JOBS=12
+
 release-debuginfo
 assertions
 enable-lsan