Re-enable copyloopvar linter (#3418)

## Changes
Add copyloopvar linter to list of enabled linters. Fix found issues.

## Why
This was supposed to be enabled
#2160 but it seems I just ran it
once at that time.

Author: denik

.golangci.yaml

@@ -15,6 +15,7 @@ linters:
     - unconvert
     - unused
     - exhaustruct
+    - copyloopvar
   settings:
     copyloopvar:
       check-alias: true

integration/bundle/spark_jar_test.go

@@ -40,7 +40,6 @@ func runSparkJarTests(t *testing.T, testCases []sparkJarTestCase, testRunner fun
 
 	// Run the tests that can run
 	for _, tc := range testCases {
-		tc := tc // Capture range variable for goroutine
 		canRun := testCanRun[tc.name]
 
 		t.Run(tc.name, func(t *testing.T) {

libs/dagrun/dagrun_test.go

@@ -77,7 +77,6 @@ func TestRun_VariousGraphsAndPools(t *testing.T) {
 	}
 
 	for _, tc := range tests {
-		tc := tc
 		for _, p := range pools {
 			t.Run(tc.name+fmt.Sprintf(" pool=%d", p), func(t *testing.T) {
 				g := NewGraph[stringWrapper]()