ctest: Remove unnecessary and ambiguous tests-from-file comment syntax

Test names can contain `#`.  Since we ignore lines that do not match any
test names anyway, "commenting" can still work without explicit syntax.
Also drop whitespace trimming for similar reasons.

Fixes: #25741

Help/manual/ctest.1.rst

@@ -242,7 +242,7 @@ Run Tests
 
  This option tells CTest to run the tests which are listed in the given
  file. The file must contain one exact test name per line.
- Lines can be commented out using a ``#``.
+ Lines that do not exactly match any test names are ignored.
  This option can be combined with the other options like
  ``-R``, ``-E``, ``-L`` or ``-LE``.
 
@@ -254,7 +254,7 @@ Run Tests
 
  This option tells CTest to NOT run the tests which are listed in the given
  file. The file must contain one exact test name per line.
- Lines can be commented out using a ``#``.
+ Lines that do not exactly match any test names are ignored.
  This option can be combined with the other options like
  ``-R``, ``-E``, ``-L`` or ``-LE``.
 

Source/CTest/cmCTestTestHandler.cxx

@@ -2037,12 +2037,9 @@ cm::optional<std::set<std::string>> cmCTestTestHandler::ReadTestListFile(
     std::set<std::string> testNames;
     std::string line;
     while (cmSystemTools::GetLineFromStream(ifs, line)) {
-      std::string trimmed = cmTrimWhitespace(line);
-      if (trimmed.empty() || (trimmed[0] == '#')) {
-        continue;
+      if (!line.empty()) {
+        testNames.insert(line);
       }
-
-      testNames.insert(trimmed);
     }
     result = std::move(testNames);
   } else {

Tests/RunCMake/CTestCommandLine/TestsFromFile-TestList.txt

@@ -1,2 +1,5 @@
 Test1
+
+est
+  Test11
 # Test11

Tests/RunCMake/ctest_test/TestsFromFile-TestList.txt

@@ -1,2 +1,5 @@
 Test1
+
+est
+  Test11
 # Test11