[Build] Declare mirror for eclipse p2 repository (elastic#117732)

The spotlight plugin directly resolves dependencies from p2 which causes

`java.io.IOException: Failed to load eclipse jdt formatter` issues if that repo is not accessible.

This is a workaround for the eclipse p2 default repository being down resulting in all our
ci jobs to fail.

The artifacts in question we wanna cache live in `~/.m2/repository`

(cherry picked from commit c35777a)

# Conflicts:
#	build-conventions/src/main/java/org/elasticsearch/gradle/internal/conventions/precommit/FormattingPrecommitPlugin.java

Author: breskeby

build-conventions/src/main/java/org/elasticsearch/gradle/internal/conventions/precommit/FormattingPrecommitPlugin.java

@@ -14,6 +14,8 @@
 import org.gradle.api.Plugin;
 import org.gradle.api.Project;
 
+import java.util.Map;
+
 /**
  * This plugin configures formatting for Java source using Spotless
  * for Gradle. Since the act of formatting existing source can interfere
@@ -66,7 +68,13 @@ public void apply(Project project) {
                 java.importOrderFile(project.getRootProject().file(importOrderPath));
 
                 // Most formatting is done through the Eclipse formatter
-                java.eclipse().configFile(project.getRootProject().file(formatterConfigPath));
+<<<<<<< HEAD
+                java.eclipse().withP2Mirrors(Map.of("https://download.eclipse.org/", "https://mirror.umd.edu/eclipse/"))
+                    .configFile(new File(elasticsearchWorkspace, formatterConfigPath)).configFile(project.getRootProject().file(formatterConfigPath));
+=======
+                java.eclipse().withP2Mirrors(Map.of("https://download.eclipse.org/", "https://mirror.umd.edu/eclipse/"))
+                    .configFile(new File(elasticsearchWorkspace, formatterConfigPath));
+>>>>>>> c35777a175f ([Build] Declare mirror for eclipse p2 repository (#117732))
 
                 // Ensure blank lines are actually empty. Since formatters are applied in
                 // order, apply this one last, otherwise non-empty blank lines can creep