Add stripIndent

Author: aaradhak

jobs/bootimagebump.Jenkinsfile

@@ -117,7 +117,7 @@ node {
                         s390x=${params.BUILD_VERSION}                                     \\
                         ppc64le=${params.BUILD_VERSION}
                     ```
-                    """.replaceAll("(?m)^(?!    plume cosa2stream|        --|        x86_64|        aarch64|        s390x|        ppc64le)\\s+", "").trim()
+                    """.stripIndent().trim()
                     shwrap ("""
                             cd installer
                             git add ${RHCOS_METADATA_FILE}