Fix mvnup PLUGIN_UPGRADES inconsistencies for compiler and exec plugins (#12172) (#12225)

maven-compiler-plugin was listed as 3.2.0 but Maven Central only has 3.2,
causing resolution failures. exec-maven-plugin had wrong groupId
(org.apache.maven.plugins) and artifactId (maven-exec-plugin), inconsistent
with getPluginUpgradesMap() which correctly uses org.codehaus.mojo:exec-maven-plugin.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: gnodet

impl/maven-cli/src/test/java/org/apache/maven/cling/invoker/mvnup/goals/PluginUpgradeStrategyTest.java

@@ -746,7 +746,7 @@ void shouldHavePredefinedPluginUpgrades() throws Exception {
                     upgrades.stream().anyMatch(upgrade -> "maven-surefire-report-plugin".equals(upgrade.artifactId()));
 
             assertTrue(hasCompilerPlugin, "Should include maven-compiler-plugin upgrade");
-            assertTrue(hasExecPlugin, "Should include maven-exec-plugin upgrade");
+            assertTrue(hasExecPlugin, "Should include exec-maven-plugin upgrade");
             assertTrue(hasSurefirePlugin, "Should include maven-surefire-plugin upgrade");
             assertTrue(hasFailsafePlugin, "Should include maven-failsafe-plugin upgrade");
             assertTrue(hasSurefireReportPlugin, "Should include maven-surefire-report-plugin upgrade");