Tests: Drop unnecessary stderr matching from RunCMake.ctest_memcheck

The Dummy*-stderr.txt files were needed only to match platform-specific
memcheck tooling output and verify that stderr is otherwise empty.  Now
that the RunCMake infrastructure knows how to strip such lines before
matching, we can simply drop these files and use the default empty
string match.

Tests/RunCMake/ctest_memcheck/DummyPurify-stderr.txt

@@ -1,3 +0,0 @@
-^((^|
-)(BullseyeCoverage|==|ctest\([0-9]+\) malloc:)[^
-]*)*$

Tests/RunCMake/ctest_memcheck/DummyValgrind-stderr.txt

@@ -1,3 +0,0 @@
-^((^|
-)(BullseyeCoverage|==|ctest\([0-9]+\) malloc:)[^
-]*)*$

Tests/RunCMake/ctest_memcheck/DummyValgrindIgnoreMemcheck-stderr.txt

@@ -1,3 +0,0 @@
-^((^|
-)(BullseyeCoverage|==|ctest\([0-9]+\) malloc:)[^
-]*)*$

Tests/RunCMake/ctest_memcheck/DummyValgrindPrePost-stderr.txt

@@ -1,3 +0,0 @@
-^((^|
-)(BullseyeCoverage|==|ctest\([0-9]+\) malloc:)[^
-]*)*$

Tests/RunCMake/ctest_memcheck/DummyValgrindTwoTargets-stderr.txt

@@ -1,3 +0,0 @@
-^((^|
-)(BullseyeCoverage|==|ctest\([0-9]+\) malloc:)[^
-]*)*$