Matrix: drop pushed gate, surface last push error in failure

Gating imageExistsInRegistry behind pushed=true skipped the registry
probe when push() threw, missing the Harbor pattern where the manifest
landed but the client got EOF on the response. Always probe the
registry after each push attempt; success there short-circuits the
loop regardless of whether push() threw. Track the last push exception
so the final reportFail message names the underlying error instead of
only saying the tag was not visible.

Author: Alexey-Rivkin

src/com/mellanox/cicd/Matrix.groovy

@@ -1192,30 +1192,30 @@ def buildImage(img, filename, extra_args, config, image) {
 def pushAndVerify(customImage, String img, config) {
     def attempts = 3
     def delaySeconds = 10
+    def lastPushError = null
 
     for (int i=1; i<=attempts; i++) {
-        def pushed = false
         try {
             customImage.push()
-            pushed = true
+            lastPushError = null
         } catch (Exception e) {
+            lastPushError = e
             config.logger.warn("docker push failed - ${img} - attempt ${i}/${attempts}: ${e.message}")
         }
 
-        if (pushed && imageExistsInRegistry(img, config)) {
+        if (imageExistsInRegistry(img, config)) {
             config.logger.info("Verified pushed image in registry - ${img}")
             return
         }
 
         if (i < attempts) {
-            if (pushed) {
-                config.logger.warn("Pushed image is not visible in registry yet - ${img} - retry ${i}/${attempts}")
-            }
+            config.logger.warn("Pushed image is not visible in registry yet - ${img} - retry ${i}/${attempts}")
             sleep(time: delaySeconds, unit: 'SECONDS')
         }
     }
 
-    reportFail('docker push', "Pushed image ${img} is not visible in registry after ${attempts} attempts")
+    def suffix = lastPushError ? " Last push error: ${lastPushError.message}" : ""
+    reportFail('docker push', "Pushed image ${img} is not visible in registry after ${attempts} attempts.${suffix}")
 }
 
 Boolean isEnvVarSet(var) {