jenkins docker change plugin installer

[danistrebel]

Description

What's changed, or what was fixed?

• Change plugin installer as the previous approach is no longer available. Details: https://github.com/jenkinsci/docker/pull/1408

Fixes: #issue

Housekeeping

(please check all that apply [x], do not edit the text)

• [x] I have run all the tests locally and they all pass.
• [x] I have followed the relevant style guide for my changes.
• [ ] PR requires full pipeline run (Run for changes only by default).

CC: @apigee-devrel-reviewers

[danistrebel]

/gcbrun

[apigee-devrel-bot]

Pipeline Report

Pipeline	Result	Elapsed Wall Time
references/cicd-pipeline	pass	558s
TOTAL PIPELINE	pass	558s

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Commit version: e87fd35