Revert "Add support for Material 3 Divider and VerticalDivider"

[CaseyHillers]

Reverts #112378

@TahaTesser this broke a few Google tests.

It seems like it's not pulling the correct color from the theme.

    final Color? color = this.color ?? defaults.color;

Googlers, see b/249195768

[TahaTesser]

Thanks! I'll take a look.

[TahaTesser]

@darrenaustin
Can you please check google tests? In the tests or visually, there is no difference in default M2 colors.

M2 template doesn't set any color and leaves to createBorderSide to resolve just like before this PR.

master	PR

[darrenaustin]

@darrenaustin Can you please check google tests? In the tests or visually, there is no difference in default M2 colors.

So a couple of unrelated issues. The tests that failed were golden tests that were using a divider with useMaterial3: true, but with default values. This PR changes those defaults, so the tests failed. I have worked with the team to update the app to use ThemeData.dividerTheme to ensure their dividers won't change when this lands.

The second issue was one I didn't catch in review that @CaseyHillers brought up above: we weren't using the DividerTheme.of in the color calculation (at least not in the M3 case).

I took the liberty of taking your PR and changing some of the color logic to fix this, as well as adding more of the properties to the generated theme data so that all the properties followed the same pattern. Hope you don't mind. The new PR is: #112655.