Fix memory leak issue with dev tools

[hehaijin]

This is to fix the memory leak identified in #1332

Each copy of client data to extension is wrapped inside a promise,
and this data is supposed to be removed and GCed but right now it's not.

in src/extension/messageAdapters.ts createPortMessageAdapter
the line port.onDisconnect.addListener creates
a closure that holds the reference to handler passed in, and only release when disconnect,
which may not happen very soon.
And in src/extension/rpc.ts createRpcClient function, the the handler holds
a reference to the promise that get data from client side.
so the promise data never got garbage collected.

Removed this event handler from onDisconnect to fix the memory leak issue.

May need to address how to properly remove it in onDisconnect, but it's lower priority.
closes #1332

[apollo-cla]

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[hehaijin]

This event handler would hold reference to listener and prevent it from garbage collected.

[jerelmiller]

Hey @hehaijin 👋

Thanks so much for this PR! I don't actually remember why I added the code to remove the onMessage event listener in onDisconnect. Googling around, I can't seem to find anything that specifies that this is needed. Perhaps I saw it somewhere and blindly copied it 😅.

In any case, this PR looks good and I think its a small enough change that should be fine. If you wouldn't mind adding a changeset to this PR, I'd be happy to get this merged and released. Appreciate all the digging you've been doing into the memory consumption of the devtools! We'd welcome any improvements you find!

[hehaijin]

Thanks @jerelmiller for reviewing. Added changeset.

[hehaijin]

@jerelmiller I have some thoughts regarding performance posted in discussion: #1337
it would be nice to know what your guys think.

[jerelmiller]

🎉 Thanks again so much for this PR!

[relativeci]

#214 Bundle Size — 851.54KiB (-0.02%).

89f7a05(current) vs 10e61ed main#212(baseline)

Warning

Bundle contains 5 duplicate packages – View duplicate packages

Bundle metrics   3 changes 1 improvement

	Current #214	Baseline #212
Initial JS	814.14KiB(-0.02%)	814.34KiB
Initial CSS	0B	0B
Cache Invalidation	8.39%	0%
Chunks	5	5
Assets	12	12
Modules	638	638
Duplicate Modules	35	35
Duplicate Code	5.2%(-0.38%)	5.22%
Packages	58	58
Duplicate Packages	4	4

Bundle size by type   1 change 1 improvement

	Current #214	Baseline #212
JS	814.14KiB (-0.02%)	814.34KiB
IMG	35.85KiB	35.85KiB
HTML	810B	810B
Other	778B	778B

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