Remove Requirement for Key Setting on Azure Client Settings (elastic#82030) (elastic#82039)

We can have a sas token or key for a given client and don't have infrastructure for
conditionally checking if either of the two is set so this commit removes the dependency
to fix the bug that you can't set these custom settings when using a SAS token.

It was somewhat tricky to test this since these validations only run when starting a node
as we're dealing with node settings so I just went with a low effort approach and randomly
used sas token auth in some ITs which would break without this change.

Co-authored-by: Dimitris Rempapis <[email protected]>

Author: original-brownbear

server/src/main/java/org/elasticsearch/common/settings/Setting.java

@@ -837,7 +837,7 @@ private Stream<String> matchStream(Settings settings) {
          * @return the raw list of dependencies for this setting
          */
         public Set<AffixSettingDependency> getDependencies() {
-            return Collections.unmodifiableSet(dependencies);
+            return dependencies;
         }
 
         @Override