[LAA] Improve convergent tests (#136758)
LoopAccessAnalysis has code for handling function calls where the
function is marked with the 'convergent' attribute, but the test
coverage is insufficient. Fix this by adding a test showing the case of
no-runtime-checks adapted from LoopDistribute, and clean up the existing
test with runtime-checks. Also regenerate the test file with
UpdateTestChecks.
