Remove unused versions of jtreg from the code-tools build

[smlambert]

Related to adoptium/TKG#762 - let's remove older unused versions of jtreg from the code-tools build.

Intention to remove:

• 6+1
• 6.1+1
• 7+1
• 7.1.1+1
• 7.2+1
• 7.3+1
• 7.5.1+1
• 7.5.2+1

Creating this issue for visibility, in case others use old versions, so they can give feedback to the topic.