PKG-1427: Reuse a named buildx builder in the e2e Jenkinsfile

[nogueiraanderson]

Bug

• The build-docker-image stage runs anonymous docker buildx create --use with no docker buildx rm; every build leaks a running buildkit container plus a named _state cache volume on the Jenkins worker, and docker system prune reclaims neither, so worker disks fill to 100% and builds fail at image pull.

Fix

• Switch to the named use-or-create idiom shared by the jenkins-pipelines cloud jobs: docker buildx use multiarch 2>/dev/null || docker buildx create --name multiarch --use.
• One shared builder per worker instead of one leak per build; recreated automatically if removed.

Tickets

• PKG-1427 (this); siblings: jenkins-pipelines#4265 (master), jenkins-pipelines#4266 (hetzner)

[it-percona-cla]

All committers have signed the CLA.

[JNKPercona]

Test Name	Result	Time
backup-enable-disable	passed	00:00:00
builtin-extensions	failure	00:00:00
cert-manager-tls	passed	00:00:00
custom-envs	passed	00:00:00
custom-tls	passed	00:00:00
database-init-sql	passed	00:00:00
demand-backup	passed	00:00:00
demand-backup-offline-snapshot	failure	00:00:00
dynamic-configuration	passed	00:00:00
finalizers	passed	00:00:00
init-deploy	passed	00:00:00
huge-pages	passed	00:00:00
major-upgrade-14-to-15	passed	00:00:00
major-upgrade-15-to-16	passed	00:00:00
major-upgrade-16-to-17	passed	00:00:00
major-upgrade-17-to-18	passed	00:00:00
ldap	passed	00:00:00
ldap-tls	passed	00:00:00
monitoring	passed	00:00:00
monitoring-pmm3	passed	00:00:00
one-pod	passed	00:00:00
operator-self-healing	passed	00:00:00
pitr	passed	00:00:00
scaling	passed	00:00:00
scheduled-backup	passed	00:00:00
self-healing	passed	00:00:00
sidecars	passed	00:00:00
standby-pgbackrest	passed	00:00:00
standby-streaming	passed	00:00:00
start-from-backup	passed	00:00:00
tablespaces	passed	00:00:00
telemetry-transfer	passed	00:00:00
upgrade-consistency	passed	00:00:00
upgrade-minor	passed	00:00:00
users	passed	00:00:00
migration-from-crunchy-standby	passed	00:00:00
migration-from-crunchy-pv	passed	00:00:00
migration-from-crunchy-backup-restore	passed	00:00:00

Summary	Value
Tests Run	38/38
Job Duration	00:06:59
Total Test Time	N/A

commit: 09218df
image: perconalab/percona-postgresql-operator:PR-1688-09218dfd8

[egegunes]

@nogueiraanderson could you please resolve conflicts?