pchreuse: remove MSVC 2008-or-older condition

Testing locally, `.idb` files are *not* made unconditionally with v71 at
least. Perhaps v90 is an outlier?

In any case, the typo introduced in 1f791eb160 (Multi-Ninja: Fix
reusable PCHs for MSVC, 2020-05-24) via !4787 (see
`cmLocalGenerator.cxx:2751` for extra space inside the quotes) was
preserved when fixing `IS_NEWER_THAN` logic in 28501fca94 (PCH PDB: Fix
misuse of IS_NEWER_THAN in timestamp check, 2021-02-21) from !5825. The
typo itself was fixed in cb46c4a918 (cmLocalGenerator: fix quoting in
generated script, 2025-06-16) via !10887 but the condition was fumbled
later in that MR's commit f78f592b78 (pchreuse: defer target existence
enforcement to generation time, 2025-06-16) in constructing `to_file`
for the script.

In the end, these typos ended up making the builds pass. In fixing it
properly in the parent commit, it exposed MSVC v71 as an outlier in
passing the tests again. Since I do not see `.idb` files with the
toolchain as tested in CI, further investigation into the build that
caused the condition to be added in the first place is required. In the
meantime, removing this check makes things happy as far as CMake's own
test suite is concerned.

Source/cmLocalGenerator.cxx

@@ -2837,18 +2837,7 @@ void cmLocalGenerator::AddPchDependencies(cmGeneratorTarget* target)
                     langFlags.find("-Zi") != std::string::npos;
                 }
 
-                // MSVC 2008 is producing both .pdb and .idb files with /Zi.
-                bool msvc2008OrLess =
-                  cmSystemTools::VersionCompare(cmSystemTools::OP_LESS,
-                                                compilerVersion, "16.0") &&
-                  compilerId == "MSVC";
-                // but not when used via toolset -Tv90
-                if (this->Makefile->GetSafeDefinition(
-                      "CMAKE_VS_PLATFORM_TOOLSET") == "v90") {
-                  msvc2008OrLess = false;
-                }
-
-                if (editAndContinueDebugInfo || msvc2008OrLess) {
+                if (editAndContinueDebugInfo) {
                   this->CopyPchCompilePdb(config, lang, target, reuseTarget,
                                           { ".pdb", ".idb" });
                 } else if (programDatabaseDebugInfo) {