Revert "fix(deps): update dependency com.google.cloud:google-cloud-monitoring-bom to v3.4.2 (googleapis#8290)"

This reverts commit 757bdb5.

Author: suztomo

google-cloud-gapic-bom/pom.xml

@@ -374,7 +374,7 @@
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-monitoring-bom</artifactId>
-        <version>3.4.2</version><!-- {x-version-update:google-cloud-monitoring:current} -->
+        <version>3.4.2-SNAPSHOT</version><!-- {x-version-update:google-cloud-monitoring:current} -->
         <type>pom</type>
         <scope>import</scope>
       </dependency>