Deprecating subclassing of Plugin

[JENKINS-31395] Footer does not work fine in some situations

[JENKINS-31776] CLI command online-node extracted from core to CLI

JENKINS-29059: Display cron run times after warnings if warnings occur.

[JENKINS-30914] Add extra logging to the queue

online-node covered by test-cases

[JENKINS-31019] Bump BCT to pickup fix.

Initial Bulgarian translation

This caused a NullPointerException since newInstance was then called reëntrantly.
Adjusting NewInstanceBindInterceptor.processed handling to behave correctly in this case.

NodePropertyTest.invisibleProperty demonstrates that the fallback for onConvert must be onConvert, not instantiate, of the delegate.

Added default attribute to enum.jelly

CLI delete-node: correction of handling an exception occurred during execution when not enough rights are on

The failure was in ClassLoader.checkCerts that throws the following
exception:

    if (pcerts != null && !compareCerts(pcerts, certs)) {
        throw new SecurityException("class \""+ name +
             "\"'s signer information does not match signer information of other classes in the same package");
    }

CLI delete-node: correction of handling an exception occurred during execution when not enough rights are on

[FIXED JENKINS-31747] Add node/npm profiles to plugin parent pom

Improve readability with a space in JDK downloading message

[JENKINS-31596] The kill switch is never relevant if you do not have RUN_SCRIPTS

This is the logical consequence of what we agreed in the CERT meeting
today, given that the 2.53.2 is public.

(cherry picked from commit d2e0f6fa)