Build: Cache Prometheus binary (opensearch-project#3261)

Author: andy-k-improving

integ-test/build.gradle

@@ -288,12 +288,15 @@ task startPrometheus(type: SpawnProcessTask) {
     mustRunAfter ':doctest:doctest'
 
     doFirst {
-        download.run {
-            src getPrometheusBinaryLocation()
-            dest new File("$projectDir/bin", 'prometheus.tar.gz')
+        File prometheusFilePath = Paths.get("$projectDir/bin", "prometheus-${prometheus_binary_version}.tar.gz").toFile()
+        if (!prometheusFilePath.exists()) {
+            download.run {
+                src getPrometheusBinaryLocation()
+                dest prometheusFilePath
+            }
         }
         copy {
-            from tarTree("$projectDir/bin/prometheus.tar.gz")
+            from tarTree("$projectDir/bin/prometheus-${prometheus_binary_version}.tar.gz")
             into "$projectDir/bin"
         }
         file("$projectDir/bin").eachDir {
@@ -310,7 +313,6 @@ task startPrometheus(type: SpawnProcessTask) {
 task stopPrometheus(type: KillProcessTask) {
     doLast {
         file("$projectDir/bin/prometheus").deleteDir()
-        file("$projectDir/bin/prometheus.tar.gz").delete()
     }
 }