…o after bkclient initialize (apache#20944)

(cherry picked from commit d9ebaf5)

…ed on topic, when dedup is enabled and no producer is there (apache#20951)

(cherry picked from commit 30073db)

…currently (apache#20971)

**Background**: when calling `pulsar-admin topics stats --get-earliest-time-in-backlog <topic name>`, Pulsar will read the first entry which is not acknowledged, and respond with the entry write time. The flow is like this:
- get the mark deleted position of the subscription
- if no backlog, response `-1`
- else read the next position of the mark deleted position, and respond with the entry write time.

**Issue**: if the command `pulsar-admin topics stats --get-earliest-time-in-backlog <topic name>` and `consumer.acknowledge` are executed at the same time, the step 2 in above flow will get a position which is larger than the last confirmed position, lead a read entry error.

| time | `pulsar-admin topics stats --get-earliest-time-in-backlog <topic name>` | `consumer.acknowledge` |
| --- | --- | --- |
| 1 | mark deleted position is `3:1` and LAC is `3:2` now |
| 2 | the check `whether has backlog` is passed |
| 3 | | acknowledged `3:2`, mark deleted position is `3:2` now |
| 4 | calculate next position: `3:3` |
| 5 | Read `3:3` and get an error: `read entry failed` |

Note: the test in PR is not intended to reproduce the issue.

Respond `-1` if the next position of the mark deleted position is larger than the LAC

(cherry picked from commit 7c96a36)

…tion check. (apache#20983)

(cherry picked from commit 43cd86d)

…MinNumRacksPerWriteQuorum not work problem. (apache#21327)

(cherry picked from commit 61a7adf)

…ic (apache#21348)

(cherry picked from commit c8a2f49)

…elete heartbeat topic (apache#21360)

Co-authored-by: fanjianye <fanjianye@bigo.sg>
Co-authored-by: Jiwei Guo <technoboy@apache.org>
(cherry picked from commit 700a29d)

…he#21398)

(cherry picked from commit e5120ec)

… in ModularLoadManagerImpl (apache#19656)

(cherry picked from commit 145e985)