Fix the JDK crawler and get rid of the hack from INFRA-2345

[lemeurherve]

Reproduction steps

Notice the use of a hack for the JDK crawler:

crawler/jdk.groovy

Lines 29 to 31 in 5b0906a

	// HACK HACK HACK INFRA-2345
	// Temporary bandaid to give up scraping and use a snapshot
	return JSONObject.fromObject(new File("jdk.hack.json").text)

jdk.hack.json is a snapshot of the last successful run dated from November 2019.

Expected Results

No hack, JDK retrieved from Oracle website or other source of truth.

Actual Results

The returned JDK list dates from November 2019.

Anything else?

Source of the hack:

• [INFRA-2345] Update center: expired certificates block tool updates helpdesk#1964 (comment)

[olamy]

could benefit from using https://github.com/foojayio/discoapi