Bump postcss and css-loader in /pinot-controller/src/main/resources #21260

Job	Run time
Pinot Compatibility Regression Testing against release-0.12.1 on compatibility-verifier/sample-test-suite	39m 44s
Pinot Integration Test Set 1 (temurin-11)	8m 26s
Pinot Compatibility Regression Testing against release-1.0.0 on compatibility-verifier/sample-test-suite	36m 10s
Pinot Unit Test Set 1 (temurin-11)	1h 1m 56s
Pinot Integration Test Set 1 (temurin-17)	8m 5s
Pinot Compatibility Regression Testing against master on compatibility-verifier/sample-test-suite	46m 0s
Pinot Unit Test Set 1 (temurin-17)	1h 2m 54s
Pinot Integration Test Set 1 (temurin-20)	7m 54s
Pinot Unit Test Set 1 (temurin-20)	59m 29s
Pinot Integration Test Set 2 (temurin-11)	10m 24s
Pinot Unit Test Set 2 (temurin-11)	10m 43s
Pinot Linter Test Set	3m 38s
Pinot Integration Test Set 2 (temurin-17)	9m 45s
Pinot Unit Test Set 2 (temurin-17)	11m 14s
Pinot Integration Test Set 2 (temurin-20)	9m 11s
Pinot Unit Test Set 2 (temurin-20)	13m 13s
Pinot Quickstart on JDK 11	21m 35s
Pinot Quickstart on JDK 17	28m 5s
Pinot Quickstart on JDK 20	20m 35s
	7h 49m 1s

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