[test][NewGVN] Use -passes=newgvn instead of -newgvn

Use the new PM syntax when specifying the pipeline in regression
tests previously running
  "opt -newgvn ..."

Instead we now do
  "opt -passes=newgvn ..."

Notice that this also changes the aa-pipeline to become the default
aa-pipeline instead of just basic-aa. Since these tests haven't been
explicitly requesting basic-aa in the past (compared to the test cases
updated in a separate patch involving "-basic-aa -newgvn") it is
assumed that the exact aa-pipeline isn't important for the validity
of the test cases. An alternative could have been to add
-aa-pipeline=basic-aa as well to the run lines, but that might just
add clutter in case the test cases do not care about the aa-pipeline.

This is another step to move away from the legacy PM syntax when
specifying passes in opt.

Differential Revision: https://reviews.llvm.org/D118341