[DTLTO][TEST] Loosen Clang driver test regexes to fix buildbots (#159158)

Make the test regexes more permissive to fix buildbot failures caused by
the merge of PR #159129. This mirrors the earlier fix in PR #148908. We
retain cross-project-test coverage to verify that the path content is
correct.

A follow-up will update the tests to robustly check the Clang executable
filename, likely along the lines of PR #159151.

Short-term unbreak to keep the buildbots green without reverting a chain
of commits.

Author: bd1976bris

clang/test/Driver/DTLTO/dtlto.c

@@ -38,7 +38,7 @@
 
 // DEFAULT: ld.lld
 // DEFAULT-SAME: "--thinlto-distributor=d.exe"
-// DEFAULT-SAME: "--thinlto-remote-compiler={{.*}}clang{{[^\"]*}}"
+// DEFAULT-SAME: "--thinlto-remote-compiler={{[^"]+}}"
 
 /// Check that nothing is forwarded when the compiler is not in LTO mode, and that
 /// appropriate unused option warnings are issued.

clang/test/Driver/DTLTO/ps5-dtlto.c

@@ -38,7 +38,7 @@
 
 // DEFAULT: prospero-lld
 // DEFAULT-SAME: "--thinlto-distributor=d.exe"
-// DEFAULT-SAME: "--thinlto-remote-compiler={{.*}}clang{{[^\"]*}}"
+// DEFAULT-SAME: "--thinlto-remote-compiler={{[^"]+}}"
 
 /// Check that the arguments are forwarded unconditionally even when the
 /// compiler is not in LTO mode.