Clean up NFR test result formatting

Problem: Some results files added extra newlines, causing our formatter to fail. Also, error log files were way too large for feasible parsing.

Solution: Remove extra newlines, and only include error logs instead of full log files.

tests/suite/reconfig_test.go

@@ -627,7 +627,6 @@ const reconfigResultTemplate = `
 {{- range .EventsBuckets }}
 	- {{ .Le }}ms: {{ .Val }}
 {{- end }}
-
 `
 
 func writeReconfigResults(dest io.Writer, results reconfigTestResults) error {

tests/suite/scale_test.go

@@ -187,7 +187,7 @@ The logs are attached only if there are errors.
 		Expect(err).ToNot(HaveOccurred())
 
 		logLines := strings.Split(logs, "\n")
-		errors := 0
+		var errors []string
 
 	outer:
 		for _, line := range logLines {
@@ -198,22 +198,24 @@ The logs are attached only if there are errors.
 			}
 			for _, substr := range substrings {
 				if strings.Contains(line, substr) {
-					errors++
+					errors = append(errors, line)
 					continue outer
 				}
 			}
 		}
 
-		// attach full logs
-		if errors > 0 {
+		// attach error logs
+		if len(errors) > 0 {
 			f, err := os.Create(fileName)
 			Expect(err).ToNot(HaveOccurred())
 			defer f.Close()
 
-			_, err = io.WriteString(f, logs)
+			for _, e := range errors {
+				_, err = io.WriteString(f, e)
+			}
 			Expect(err).ToNot(HaveOccurred())
 		}
-		return errors
+		return len(errors)
 	}
 
 	runTestWithMetricsAndLogs := func(testName, testResultsDir string, test func()) {
@@ -797,8 +799,6 @@ var _ = Describe("Zero downtime scale test", Ordered, Label("nfr", "zero-downtim
 	})
 
 	AfterAll(func() {
-		_, err := fmt.Fprintln(outFile)
-		Expect(err).ToNot(HaveOccurred())
 		Expect(outFile.Close()).To(Succeed())
 
 		// restoring NGF shared among tests in the suite