Fix rangeslider reset after zooming out - #8098

Description

Closes #6903.

The existing rangeslider test did not fully cover resetting an autoranged rangeslider after the axis range had been expanded. This is a regression introduced in v1.40.0.

This PR also fixes the same reset issue for rangesliders with an explicitly configured range, for example:

      "rangeslider": {
        "range": [-2, 4]
      },

Existing test updates

I think the effective rangeslider range can expand as needed to cover the current axis range, but it should not overwrite the user-specified rangeslider range.

So, I updated the existing tests:

1. the input range should remain unchanged
2. the effective range in _fullLayout can expand to cover the current axis range

Results

Using mock: http://localhost:3000/devtools/test_dashboard/index.html#range_slider_initial_expanded

Click Zoom out 5 times, then click Reset axes (the same issue occurs with Autoscale).

Before:

After:

Using mock: http://localhost:3000/devtools/test_dashboard/index.html#range_slider_multiple

The heatmap rangeslider has an explicitly configured range.

Click Zoom out 5 times, then click Reset axes (the same issue occurs with Autoscale).

Before:

After: