Intermittent Electron Integration test failure: Unknown method $extensionTestsExecute

[jmcphers]

This failure has been showing up frequently in our Electron Integration CI tests:

[18161:0228/234323.998548:INFO:CONSOLE(418)]
"Error: Unknown method $extensionTestsExecute on actor ExtHostCustomEditors",
source: vscode-file://vscode-app/home/runner/work/positron/positron/out/vs/workbench/services/extensions/common/abstractExtensionService.js (418)

Here are a bunch of examples of full test runs/logs from a variety of PRs by a variety of developers:

https://github.com/posit-dev/positron/actions/runs/7876449164/job/21490489953
https://github.com/posit-dev/positron/actions/runs/8088115350/attempts/1?pr=2358
https://github.com/posit-dev/positron/actions/runs/8088115350/attempts/2?pr=2358
https://github.com/posit-dev/positron/actions/runs/8090350064/job/22107697614?pr=2356
https://github.com/posit-dev/positron/actions/runs/8090241463/job/22107412078?pr=2360

Sometimes, CI tests have to be re-run two or three times to get a clean run.

We should either figure out why this test is flaky (and fix it so it isn't) or disable it.

Slack thread with more discussion: https://positpbc.slack.com/archives/C04FPQK3H9C/p1709164149296819

[petetronic]

We disabled the Electron Integration tests on CI as it was blocking a significant number of PRs. We need to ensure it runs reliably before re-enabling.