[2.x] Revert IDE helpers

[ycs77]

Relation PR: #654, #674 (These PRs have no conflicts and can all be merged)

Because IDE helpers caused trouble, so revert #413 and #625.

---

The above Illuminate\Testing part of the IDE helpers was created by @claudiodekker, I'm not the author, so I didn't remove it.

[SamMakesCode]

Hope this gets merged - it's small, but a great QOL change

[siarheipashkevich]

@ycs77 please merge it

[ycs77]

I can't merge it because I'm not the maintainer, I do not have permission.😭

[ycs77]

@taylorotwell @joetannenbaum could you merge this PR and #654, #674?

[joetannenbaum]

Sorry, what trouble are they causing?

[ycs77]

Sorry, what trouble are they causing?

Since I released the IDE helper update (#413, #625) before, many users have reported that the IDE IntelliSense is broken (#625 (comment), #654), although they don't use IDE helper, so this PR will revert the PRs that caused the problem.

Regarding the PR #674 and #654 on the 1.x branch, I think merging it will fix this issue for the users to using 1.x, it just removes the IDE helper file, will not modify any current features, @joetannenbaum can you consider merging it?

[ycs77]

Then I add some changes about these PRs:

• [1.x] remove IDE helpers from package #654
  • Ignore export _ide_helpers.php in .gitattributes
• [1.x] Revert IDE helpers #674
  • Remove IDE helpers with my added
• [2.x] Revert IDE helpers #675 (current PR)
  • Ignore export _ide_helpers.php in .gitattributes
  • Remove IDE helpers with my added

If ignore export _ide_helpers.php in .gitattributes, then will not download the _ide_helpers.php in running composer require.