CTest: Restore running dashboard client Test step with modified files
Since !5154 (merged),
ctest no longer runs tests if there are errors before the full set of tests is
defined. Such errors were previously treated more like warnings.
The change exposed some cases where we were issuing an error message but
proceeding to run tests anyway. The above commit downgraded one such
DartConfiguration.tcl) to a warning explicitly in order
to restore its former warning-like semantics.
Downgrade the Update step's diagnostic about modified or conflicting files to a warning for the same reason.
Fixes: #21783 (closed)