Revert etcd client version

[style95]

Description

This is to fix #5317 by reverting 4007766.
It seems the version of gprc-core module in the ETCD client conflicts with akka-grpc module.

I am curious how it passed all checks in the first place, but anyway it would be the easiest way to resolve it for now.

I think we need to upgrade both modules at once.

Related issue and scope

• I opened an issue to propose and discuss this change (#????)

My changes affect the following components

• API
• Controller
• Message Bus (e.g., Kafka)
• Loadbalancer
• Scheduler
• Invoker
• Intrinsic actions (e.g., sequences, conductors)
• Data stores (e.g., CouchDB)
• Tests
• Deployment
• CLI
• General tooling
• Documentation

Types of changes

• Bug fix (generally a non-breaking change which closes an issue).
• Enhancement or new feature (adds new functionality).
• Breaking change (a bug fix or enhancement which changes existing behavior).

Checklist:

• I signed an Apache CLA.
• I reviewed the style guides and followed the recommendations (Travis CI will check :).
• I added tests to cover my changes.
• My changes require further changes to the documentation.
• I updated the documentation where necessary.

[style95]

ok, I found there are only unit tests in the scheduler CI tests.
This will guarantee the sanity of the critical path of the scheduler.
#5308

[ningyougang]

Seems we can't use higher version forever?

[style95]

As I said above, we can upgrade both etcd client and akka-grpc module.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 76.19%. Comparing base (9be427c) to head (ab25b6f).
Report is 92 commits behind head on master.

❗ There is a different number of reports uploaded between BASE (9be427c) and HEAD (ab25b6f). Click for more details.

HEAD has 7 uploads less than BASE

Flag	BASE (9be427c)	HEAD (ab25b6f)
	12	5

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5318      +/-   ##
==========================================
- Coverage   81.23%   76.19%   -5.05%     
==========================================
  Files         239      239              
  Lines       14242    14242              
  Branches      604      604              
==========================================
- Hits        11570    10851     -719     
- Misses       2672     3391     +719     

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[style95]

I merged it as no activation can be invoked with the current master.