Update Sync error pixels

[ayoy]

Task/Issue URL: https://app.asana.com/0/1201621708115095/1207559244852258/f

Description: Rename count limit exceeded as object limit exceeded and add "Too Many Requests" pixels.

Steps to test this PR: Since this change doesn't modify any logic related to processing errors, it's enough that you verify that pixel names are correct. The simplest is to add this snippet of code at the bottom of AppDelegate's applicationDidFinishLaunching:

Pixel.fire(pixel: .syncBookmarksObjectLimitExceededDaily)
Pixel.fire(pixel: .syncCredentialsObjectLimitExceededDaily)
Pixel.fire(pixel: .syncBookmarksRequestSizeLimitExceededDaily)
Pixel.fire(pixel: .syncCredentialsRequestSizeLimitExceededDaily)
Pixel.fire(pixel: .syncBookmarksTooManyRequestsDaily)
Pixel.fire(pixel: .syncCredentialsTooManyRequestsDaily)
Pixel.fire(pixel: .syncSettingsTooManyRequestsDaily)

Then run the app and check the log. Compare output with what's expected in the Asana task.

Definition of Done (Internal Only):

• [ ] Does this PR satisfy our Definition of Done?

Copy Testing:

• [ ] Use of correct apostrophes in new copy, ie ’ rather than '

Orientation Testing:

• [ ] Portrait
• [ ] Landscape

Device Testing:

• [ ] iPhone SE (1st Gen)
• [ ] iPhone 8
• [ ] iPhone X
• [ ] iPhone 14 Pro
• [ ] iPad

OS Testing:

• [ ] iOS 15
• [ ] iOS 16
• [ ] iOS 17

Theme Testing:

• [ ] Light theme
• [ ] Dark theme

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Internal references:

Software Engineering Expectations Technical Design Template