Collect frequencies before processing sweeps

[hay-k]

Processed sweeps uses frequency from characterization section. This leads to inconsistency when user updates the frequency of native pulse, but does not update the characterization section (e.g. readout_frequency). This change fixes this inconsistency.

All of this is being removed for 0.2 release (https://github.com/qiboteam/qibolab/pull/885). This fix is needed for short term, before the realease.

Checklist:

• [ ] Reviewers confirm new code works as expected.
• [ ] Tests are passing.
• [ ] Coverage does not decrease.
• [ ] Documentation is updated.

[codecov[bot]]

Codecov Report

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

Project coverage is 66.64%. Comparing base (b93ee1b) to head (5f5f54a).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #902 +/- ## ======================================= Coverage 66.64% 66.64% ======================================= Files 55 55 Lines 5954 5954 ======================================= Hits 3968 3968 Misses 1986 1986 ``` | [Flag](https://app.codecov.io/gh/qiboteam/qibolab/pull/902/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qiboteam) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/qiboteam/qibolab/pull/902/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qiboteam) | `66.64% <100.00%> (ø)` | | 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=qiboteam#carryforward-flags-in-the-pull-request-comment) to find out more.

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