Migrate from Random() to SecureRandom()

[carloea2]

Feature Summary

Improve Auth secret generation by replacing the previous random hex string builder with a SecureRandom-based implementation that produces fixed-length 32-character hex strings in a more robust and portable way.

texera/common/config/src/main/scala/org/apache/texera/config/AuthConfig.scala

Lines 48 to 55 in 3e46cea

	private def getRandomHexString: String = {
	val bytes = 32
	val r = new Random()
	val sb = new StringBuffer
	while (sb.length < bytes)
	sb.append(Integer.toHexString(r.nextInt()))
	sb.toString.substring(0, bytes)
	}

Proposed Solution or Design

Update random hex string generation to use SecureRandom and fixed-width hexadecimal output.

Impact / Priority

(P2)Medium – useful enhancement

Affected Area

No response