rptest: tolerate leadership changes in chunk read tests

[nvartolomei]

DeleteRandomChunks worker must refresh knowledge about current leader otherwise it might act on an unrelated node, report that it was unable to delete any chunks, and fail the test.

Spotted in a backport build https://buildkite.com/redpanda/redpanda/builds/51354#0190a1a8-8687-4687-b3c6-e0ac3c9f55cc

Backports Required

• none - not a bug fix
• none - this is a backport
• none - issue does not exist in previous branches
• none - papercut/not impactful enough to backport
• v24.1.x
• v23.3.x
• v23.2.x

Release Notes

• none

[nvartolomei]

This test has another problem when leadership changes in the metric check btw. Ignoring it for now.

m = MetricCheck(self.logger,
                        self.redpanda,
                        self.redpanda.partitions(self.topic)[0].leader,
                        [metric],
                        labels={
                            'namespace': 'kafka',
                            'topic': self.topic,
                            'partition': '0',
                        })

[vbotbuildovich]

ducktape was retried in https://buildkite.com/redpanda/redpanda/builds/51357#0190a253-3991-4d57-bc27-7efddaa75771

[nvartolomei]

All failures are unrelated and inside CertificateRevocationTest which have nothing to do with this PR which changes only a specific test.

• CI Failure (Expected an exception) in CertificateRevocationTest.test_pp_api #20570
• redpanda failed to start in the same test

@dotnwat please help merge this 🙇

[vbotbuildovich]

/backport v24.1.x

[vbotbuildovich]

/backport v23.3.x