Store: Make initial sync more robust

Added re-try mechanism for store inital sync, where if the initial sync fails, it tries to do the initial sync again every 5 seconds for 15 seconds duration (total 3 re-tries for initial sync of store).

Signed-off-by: Kartik-Garg <kartik.garg@infracloud.io>

CHANGELOG.md

@@ -25,7 +25,6 @@ We use *breaking :warning:* to mark changes that are not backward compatible (re
 - [#6044](https://github.com/thanos-io/thanos/pull/6044) Receive: mark ouf of window errors as conflict, if out-of-window samples ingestion is activated
 - [#6050](https://github.com/thanos-io/thanos/pull/6050) Store: Re-try bucket store initial sync upon failure.
 - [#6066](https://github.com/thanos-io/thanos/pull/6066) Tracing: fixed panic because of nil sampler
-- [#6050](https://github.com/thanos-io/thanos/pull/6050) Store: Re-try bucket store initial sync upon failure.
 
 ### Changed