pygmt.grdtrack: Remove the warning about the incorrect parameter order of 'points, grid' (warned since v0.7.0)

[seisman]

Description of proposed changes

In PR #1867, we changed the parameter order from "points, grid" to "grid, points", and raises a warning about incorrect parameter order. The PR first appeared in v0.7.0 and is expected to be removed in v0.9.0.

This PR removes the warning.

Fixes #

Reminders

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• Add tests for new features or tests that would have caught the bug that you're fixing.
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