Exclude .triggered-watches from indices cleanup in REST tests (#131235)

Some tests were seeing an unexpected warning header from wiping all
indices in the test cleanup, caused by the `.triggered-watches` data
stream being present. We exclude the backing indices of this data stream
from the indices wipe to avoid the warning header. The presence of this
data stream shouldn't intefere with tests, and any tests that do
interact with that data stream should assert/control its state by
themselves to ensure consistency.

Fixes #129682

Author: nielsbauman

test/framework/src/main/java/org/elasticsearch/test/rest/ESRestTestCase.java

@@ -1228,7 +1228,7 @@ protected static void wipeAllIndices(boolean preserveSecurityIndices) throws IOE
         try {
             // remove all indices except some history indices which can pop up after deleting all data streams but shouldn't interfere
             final List<String> indexPatterns = new ArrayList<>(
-                List.of("*", "-.ds-ilm-history-*", "-.ds-.slm-history-*", "-.ds-.watcher-history-*")
+                List.of("*", "-.ds-ilm-history-*", "-.ds-.slm-history-*", "-.ds-.watcher-history-*", "-.ds-.triggered_watches-*")
             );
             if (preserveSecurityIndices) {
                 indexPatterns.add("-.security-*");