fix dropdown position when coverTrigger is false

[RaquelAM]

Proposed changes

Correction of the calculation of the position of the dropdown when the coverTrigger option is false and the dropdown is near the bottom of the window.
This PR fixes issue #6279, related to the position of the dropdown of the autocomplete component.

Screenshots (if appropriate) or codepen:

Types of changes

• [x ] Bug fix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to change).

Checklist:

• [ x] I have read the CONTRIBUTING document.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[DanielRuf]

Merged at materializecss@7df9e65 and materializecss@ea662b5