[test] Fix mix of variable use/def and regex match

[test] Fix mix of variable use/def and regex match

LLVM test Transforms/GlobalSplit/basic.ll mixes variable definition and
variable use with regex matching of end of line. Mixing end of line
matching with variable definition will work but not record the end of
line in the string variable. Mixing end of line with variable use will
ignore end of line and cause an error once D98691 is landed.

This commit moves the end of line matching out of the string subtitution
blocks.

Reviewed By: tejohnson

Differential Revision: https://reviews.llvm.org/D98854