Move project-related tests from MetadataTests to ProjectMetadataTests (elastic#130846)

The main goal was to get rid of loads of usages of deprecated methods in
`Metadata` and its builder, but I figured it made more sense to move
these tests to a more appropriate test class. These changes mainly
consist of a copy-paste from one test class to another, and using
`ProjectMetadata` objects (and its builders) instead of `Metadata`
objects.

Author: nielsbauman

server/src/main/java/org/elasticsearch/cluster/metadata/Metadata.java

@@ -1499,12 +1499,6 @@ public Builder put(String name, ComponentTemplate componentTemplate) {
             return this;
         }
 
-        @Deprecated(forRemoval = true)
-        public Builder removeComponentTemplate(String name) {
-            getSingleProject().removeComponentTemplate(name);
-            return this;
-        }
-
         @Deprecated(forRemoval = true)
         public Builder componentTemplates(Map<String, ComponentTemplate> componentTemplates) {
             getSingleProject().componentTemplates(componentTemplates);
@@ -1523,12 +1517,6 @@ public Builder put(String name, ComposableIndexTemplate indexTemplate) {
             return this;
         }
 
-        @Deprecated(forRemoval = true)
-        public Builder removeIndexTemplate(String name) {
-            getSingleProject().removeIndexTemplate(name);
-            return this;
-        }
-
         @Deprecated(forRemoval = true)
         public Builder dataStreams(Map<String, DataStream> dataStreams, Map<String, DataStreamAlias> dataStreamAliases) {
             getSingleProject().dataStreams(dataStreams, dataStreamAliases);
@@ -1557,11 +1545,6 @@ public Builder removeDataStream(String name) {
             return this;
         }
 
-        @Deprecated(forRemoval = true)
-        public boolean removeDataStreamAlias(String aliasName, String dataStreamName, boolean mustExist) {
-            return getSingleProject().removeDataStreamAlias(aliasName, dataStreamName, mustExist);
-        }
-
         public Builder putCustom(String type, ClusterCustom custom) {
             customs.put(type, Objects.requireNonNull(custom, type));
             return this;