plugins.txt: freeze plugins to working versions

We ran into a version mismatch between jenkins and the plugins
while setting up jenkins in the staging cluster. Lets freeze the
package versions to avoid the mismatch.

jenkins/controller/plugins.txt

@@ -1,15 +1,15 @@
-github-oauth
-configuration-as-code
-slack
-job-dsl
-matrix-auth
-aws-credentials
-basic-branch-build-strategies
-configuration-as-code-groovy
-timestamper
-build-token-root
-github
-workflow-api
-ssh-credentials
-pipeline-github
-pipeline-utility-steps
+github-oauth:0.38
+configuration-as-code:1429.v09b_044a_c93de
+slack:608.v19e3b_44b_b_9ff
+job-dsl:1.79
+matrix-auth:3.1.2
+aws-credentials:1.12.70
+basic-branch-build-strategies:1.3.2
+configuration-as-code-groovy:1.1
+timestamper:1.17
+build-token-root:1.9
+github:1.34.3
+workflow-api:1153.vb_912c0e47fb_a_
+ssh-credentials:277.v95c2fec1c047
+pipeline-github:2.8-138.d766e30bb08b
+pipeline-utility-steps:2.12.1