Increase yarn timeout when installing packages

[Charles-Gagnon]

Been seeing a lot of failures similar to this lately in CI builds (where we aren't currently caching packages) :

https://github.com/microsoft/azuredatastudio/pull/13330/checks?check_run_id=1382218824

Tue, 10 Nov 2020 21:47:37 GMT
yarn install v1.22.5
Tue, 10 Nov 2020 21:47:37 GMT
$ node build/npm/preinstall.js
Tue, 10 Nov 2020 21:47:38 GMT
[1/4] Resolving packages...
Tue, 10 Nov 2020 21:47:39 GMT
[2/4] Fetching packages...
Tue, 10 Nov 2020 21:48:56 GMT
info There appears to be trouble with your network connection. Retrying...
Tue, 10 Nov 2020 21:49:06 GMT
info There appears to be trouble with your network connection. Retrying...
Tue, 10 Nov 2020 21:49:30 GMT
info There appears to be trouble with your network connection. Retrying...
Tue, 10 Nov 2020 21:49:39 GMT
info There appears to be trouble with your network connection. Retrying...
Tue, 10 Nov 2020 21:50:04 GMT
info There appears to be trouble with your network connection. Retrying...
Tue, 10 Nov 2020 21:50:13 GMT
info There appears to be trouble with your network connection. Retrying...
Tue, 10 Nov 2020 21:50:38 GMT
info There appears to be trouble with your network connection. Retrying...
Tue, 10 Nov 2020 21:51:12 GMT
error An unexpected error occurred: "https://registry.yarnpkg.com/rxjs/-/rxjs-5.4.0.tgz: ESOCKETTIMEDOUT".
Tue, 10 Nov 2020 21:51:12 GMT
info If you think this is a bug, please open a bug report with the information provided in "/Users/runner/work/azuredatastudio/azuredatastudio/yarn-error.log".
Tue, 10 Nov 2020 21:51:12 GMT
info Visit https://yarnpkg.com/en/docs/cli/install for documentation about this command.

One of the suggested workarounds is to increase the default timeout per yarnpkg/yarn#6115 so trying that to see if it helps.

[coveralls]

Pull Request Test Coverage Report for Build 356807101

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 4 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.01%) to 40.244%

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Files with Coverage Reduction	New Missed Lines	%
extensions/notebook/src/jupyter/serverInstance.ts	4	73.81%

Totals
Change from base Build 356661241:	-0.01%
Covered Lines:	21170
Relevant Lines:	48307

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💛 - Coveralls