Revert "build(deps): update dependency org.jacoco:jacoco-maven-plugin to v0.8.9" (#2367)

* Revert "build(deps): update dependency org.jacoco:jacoco-maven-plugin to v0.8.9 (#2363)"

This reverts commit d6ccb52.

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: olavloite

README.md

@@ -50,7 +50,7 @@ If you are using Maven without the BOM, add this to your dependencies:
 If you are using Gradle 5.x or later, add this to your dependencies:
 
 ```Groovy
-implementation platform('com.google.cloud:libraries-bom:26.11.0')
+implementation platform('com.google.cloud:libraries-bom:26.12.0')
 
 implementation 'com.google.cloud:google-cloud-spanner'
 ```

google-cloud-spanner/pom.xml

@@ -29,7 +29,7 @@
       <plugin>
         <groupId>org.jacoco</groupId>
         <artifactId>jacoco-maven-plugin</artifactId>
-        <version>0.8.9</version>
+        <version>0.8.8</version>
         <executions>
           <execution>
             <goals>