Change default value of `get_elevation` to False

[kujaku11]

In theory this is a good idea, but in practice it is costly and slow. Change the default value to False when reading in a transfer function. The user then has the option to look up elevation if they want.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (7017e0e) 84.00% compared to head (18f535e) 84.02%. Report is 2 commits behind head on main.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #191 +/- ## ========================================== + Coverage 84.00% 84.02% +0.01% ========================================== Files 269 269 Lines 20161 20161 ========================================== + Hits 16937 16940 +3 + Misses 3224 3221 -3 ``` | [Flag](https://app.codecov.io/gh/kujaku11/mt_metadata/pull/191/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JP) | Coverage Δ | | |---|---|---| | [tests](https://app.codecov.io/gh/kujaku11/mt_metadata/pull/191/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JP) | `84.02% <100.00%> (+0.01%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JP#carryforward-flags-in-the-pull-request-comment) to find out more.

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