[BEAM-10991] Cherrypick #12980 to 2.25.0: Revert "[BEAM-8543] Dataflow streaming timers are not strictly time ordered when set earlier mid-bundle (#11924)"

[kennknowles]

This change is a serious regression in 2.24.0 so should be cherrypicked back to 2.25.0

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Post-Commit Tests Status (on master branch)

Lang	SDK	Dataflow	Flink	Samza	Spark	Twister2
Go		---		---		---
Java
Python				---		---
XLang		---		---		---

Pre-Commit Tests Status (on master branch)

---	Java	Python	Go	Website	Whitespace	Typescript
Non-portable
Portable	---		---	---	---	---

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[robinyqiu]

LGTM

[codecov]

Codecov Report

Merging #12993 into release-2.25.0 will increase coverage by 0.05%.
The diff coverage is n/a.

@@ Coverage Diff @@## release-2.25.0 #12993 +/- ##
==================================================
+ Coverage 82.30% 82.36% +0.05% 
==================================================
Files 455 455 Lines 54589 54948 +359 ==================================================
+ Hits 44931 45257 +326 - Misses 9658 9691 +33 

Impacted Files	Coverage Δ
...ks/python/apache_beam/runners/worker/sdk_worker.py	88.80% <0.00%> (-0.18%)	⬇️
...nners/portability/fn_api_runner/worker_handlers.py	80.75% <0.00%> (+0.17%)	⬆️
sdks/python/apache_beam/transforms/util.py	95.63% <0.00%> (+0.18%)	⬆️
sdks/python/apache_beam/io/gcp/bigquery.py	81.02% <0.00%> (+0.30%)	⬆️
sdks/python/apache_beam/runners/common.py	89.20% <0.00%> (+0.44%)	⬆️
sdks/python/apache_beam/io/localfilesystem.py	91.66% <0.00%> (+0.75%)	⬆️
...ks/python/apache_beam/runners/worker/data_plane.py	89.90% <0.00%> (+1.22%)	⬆️
sdks/python/apache_beam/io/gcp/bigquery_tools.py	89.88% <0.00%> (+1.76%)	⬆️

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[kennknowles]

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