TEZ-4649: Java21 upgrade made TestAnalyzer#testWithATS flaky - change entry to nanotime precision

[abstractdog]

This PR is to change System.currentTimeMillis() to System.nanoTime() in ATSImportTool, see details in Jira.

[ayushtkn]

If the build is green. Changes LGTM

[maheshrajus]

+1, LGTM

[tez-yetus]

💔 -1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	27m 51s		Docker mode activated.
			_ Prechecks _
+1 💚	dupname	0m 0s		No case conflicting files found.
+0 🆗	detsecrets	0m 0s		detect-secrets was not available.
+1 💚	@author	0m 0s		The patch does not contain any @author tags.
-1 ❌	test4tests	0m 0s		The patch doesn't appear to include any new or modified tests. Please justify why no new tests are needed for this patch. Also please list what manual steps were performed to verify this patch.
			_ master Compile Tests _
+1 💚	mvninstall	11m 44s		master passed
+1 💚	compile	0m 35s		master passed
+1 💚	checkstyle	0m 55s		master passed
+1 💚	javadoc	0m 31s		master passed
+0 🆗	spotbugs	1m 37s		tez-plugins/tez-history-parser in master has 21 extant spotbugs warnings.
			_ Patch Compile Tests _
+1 💚	mvninstall	0m 50s		the patch passed
+1 💚	codespell	0m 32s		No new issues.
+1 💚	compile	0m 21s		the patch passed
+1 💚	javac	0m 21s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	checkstyle	0m 8s		the patch passed
+1 💚	javadoc	0m 11s		the patch passed
+1 💚	spotbugs	0m 55s		the patch passed
			_ Other Tests _
+1 💚	unit	2m 26s		tez-history-parser in the patch passed.
+1 💚	asflicense	0m 13s		The patch does not generate ASF License warnings.
		50m 9s

Subsystem	Report/Notes
Docker	ClientAPI=1.51 ServerAPI=1.51 base: https://ci-hadoop.apache.org/job/tez-multibranch/job/PR-431/1/artifact/out/Dockerfile
GITHUB PR	#431
Optional Tests	dupname asflicense javac javadoc unit spotbugs checkstyle codespell detsecrets compile
uname	Linux b98443236058 5.15.0-144-generic #157-Ubuntu SMP Mon Jun 16 07:33:10 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	/home/jenkins/jenkins-agent/workspace/tez-multibranch_PR-431/src/.yetus/personality.sh
git revision	master / 8042f6a
Default Java	Ubuntu-21.0.8+9-Ubuntu-0ubuntu124.04.1
Test Results	https://ci-hadoop.apache.org/job/tez-multibranch/job/PR-431/1/testReport/
Max. process+thread count	701 (vs. ulimit of 5500)
modules	C: tez-plugins/tez-history-parser U: tez-plugins/tez-history-parser
Console output	https://ci-hadoop.apache.org/job/tez-multibranch/job/PR-431/1/console
versions	git=2.43.0 maven=3.8.7 spotbugs=4.9.3 codespell=2.0.0
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