fix: reBufferingGoal is not respected

[Iragne]

Fixes #6355

it's still in draft until having proper unit tests to control this

This PR is doing the following
At startup time and at buffering it will set the playback rate to 0. like it was before and reset it to the default value we no buffer.
I'm still passing all the unit test but i'm still thinging if we have an impact with the live catchup feature that is changing the playback rate.

Maybe we should just re introduce the isBuffering_ value in playbackrate class.
Happy to do it if you think so

here the link the PR that introduce the regression
https://github.com/shaka-project/shaka-player/pull/5696/files#diff-274a4cc3948f85eed18f86e04c6260b93faa97b995d38f0e3b1af618fd01fab7L34

BEGIN_COMMIT_OVERRIDE
chore: Reverted, do not include in release notes
END_COMMIT_OVERRIDE

[shaka-bot]

Incremental code coverage: 100.00%

[joeyparrish]

@avelad, you made the change to stop using playbackRate of 0 to manage buffering state. This would reintroduce a smaller version of that, by explicitly setting playbackRate to 0 when we enter a buffering state, but without so much machinery to manage things. It also has the side-effect of reverting to defaultPlaybackRate after a buffering event, instead of the playbackRate explicitly chosen by the user or by the catch-up logic.

@avelad, I would prefer you look at this and make recommendations.

[Iragne]

@avelad thanks

[avelad]

@joeyparrish can you review it? Thanks!

[Iragne]

Gentle ask to @joeyparrish if you have time ;) thanks a lot

[avelad]

@theodab @joeyparrish can you review it again? Thanks!

Reviewed by Alvaro

[joeyparrish]

This appears to be causing test failures on Tizen.

[joeyparrish]

Specifically, this causes these two failures on Tizen 100% of the time:

Player
    rebufferGoal
      ✗ state orchestration and buffer length [Safari 3.0 (Tizen 3.0)]
	Error: Expected 23.801 to be greater than or equal 25.
	    at <Jasmine>
	    at _callee45$ (test/player_integration.js:1022:34 <- test/player_integration.js:1595:42)
	    at tryCatch (node_modules/@babel/polyfill/dist/polyfill.js:6473:40)
	    at GeneratorFunctionPrototype.invoke [as _invoke] (node_modules/@babel/polyfill/dist/polyfill.js:6[70](https://github.com/shaka-project/shaka-player/actions/runs/8976237248/job/24654981074#step:10:71)2:22)


  Player Src Equals
    ✗ can control trick play rate [Safari 3.0 (Tizen 3.0)]
	Error: Expected 0 to be 2.
	    at <Jasmine>
	    at _callee11$ (test/player_src_equals_integration.js:184:32 <- test/player_src_equals_integration.js:311:40)
	    at tryCatch (node_modules/@babel/polyfill/dist/polyfill.js:64[73](https://github.com/shaka-project/shaka-player/actions/runs/8976237248/job/24654981074#step:10:74):40)
	    at GeneratorFunctionPrototype.invoke [as _invoke] (node_modules/@babel/polyfill/dist/polyfill.js:6702:22)

	Error: Expected false to be true.
	    at <Jasmine>
	    at _callee11$ (test/player_src_equals_integration.js:190:30 <- test/player_src_equals_integration.js:319:38)
	    at tryCatch (node_modules/@babel/polyfill/dist/polyfill.js:6473:40)
	    at GeneratorFunctionPrototype.invoke [as _invoke] (node_modules/@babel/polyfill/dist/polyfill.js:6702:22)

	Error: Expected 0 to be 1.
	    at <Jasmine>
	    at _callee11$ (test/player_src_equals_integration.js:197:32 <- test/player_src_equals_integration.js:327:40)
	    at tryCatch (node_modules/@babel/polyfill/dist/polyfill.js:6473:40)
	    at GeneratorFunctionPrototype.invoke [as _invoke] (node_modules/@babel/polyfill/dist/polyfill.js:6702:22)

As seen here when testing v4.8.2: https://github.com/shaka-project/shaka-player/actions/runs/8976237248/job/24654981074

I am reverting this before v4.8.2 goes out. It has not been in a release yet.

[joeyparrish]

Reverted by #6540