Bump spectator version to 1.9.0 (#18887)

Bump to Spectator version (1.9.0). Latest version is 1.9.3 but as we don't need anything in 1.9.1-1.9.3, I'd prefer to bump to stable major versions.

Author: jtuglu1

extensions-contrib/spectator-histogram/pom.xml

@@ -38,7 +38,7 @@
     <dependency>
       <groupId>com.netflix.spectator</groupId>
       <artifactId>spectator-api</artifactId>
-      <version>1.7.0</version>
+      <version>1.9.0</version>
     </dependency>
     <dependency>
       <groupId>com.google.guava</groupId>