bugfix:MergedSendRunnable can be closed by accident

[CoffeeLatte007]

Ⅰ. Describe what this PR did

#724.
1.In the MergedSendRunnable class, the connect method can throw a FrameworkException that causes the run method to permanently close.
2.MessageFuture will wait until the timeout, which I've optimized.

Ⅱ. Does this pull request fix one issue?

Ⅲ. Why don't you add test cases (unit test/integration test)?

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[codecov-io]

Codecov Report

Merging #725 into develop will decrease coverage by 0.02%.
The diff coverage is 0%.

@@              Coverage Diff              @@
##             develop     #725      +/-   ##
=============================================
- Coverage      32.75%   32.72%   -0.03%     
  Complexity       924      924              
=============================================
  Files            229      229              
  Lines           8937     8943       +6     
  Branches        1088     1090       +2     
=============================================
  Hits            2927     2927              
- Misses          5662     5668       +6     
  Partials         348      348

Impacted Files	Coverage Δ	Complexity Δ
...scar/core/rpc/netty/AbstractRpcRemotingClient.java	22.39% <0%> (-0.73%)	7 <0> (ø)

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[zhangthen]

Well done.