Switch to a BOM

[jglick]

May as a side effect fix a PCT failure reported by @bmunozm, probably caused by mismatch between workflow-support versions in primary and tests classifier:

java.io.IOException: Pipeline: Groovy version 2.71 failed to load.
 - Pipeline: Supporting APIs version 2.17 is older than required. To fix, install version 3.3 or later.

[batmat]

LGTM

[oleg-nenashev]

K8s Plugin is already updated to BOM in the new release, so I have no problem with that

[jglick]

One test failure just needs a merge of #133. The other is

org.junit.ComparisonFailure: 
expected:<test key[]> but was:<test key[
]>
	at org.junit.Assert.assertEquals(Assert.java:115)
	at org.junit.Assert.assertEquals(Assert.java:144)
	at hudson.plugins.mercurial.HgExeFunctionalTest.credentialsSSHKeyTest(HgExeFunctionalTest.java:102)

which I presume is just picking up jenkinsci/ssh-credentials-plugin#33.