Migrates dropdown in iteration_report.vue to Pajamas disclosure

What does this MR do and why?

Migrates dropdown in iteration_report.vue to Pajamas disclosure

Changelog: changed

EE: true

Screenshots or screen recordings

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Case	Before	After
Manual cadence
Automatic cadence

How to set up and validate locally

Note: Creating an iteration cadence or an iteration is only possible at the group level, not at the project level.

Note: This is an EE feature.

Creating a manual iteration

1. Go to a group. In the left navigation, click on Plan > Iterations.

2. Click button New iteration cadence.

3. Fill out the fields, uncheck Enable automatic scheduling and click Create cadence.

4. On the iterations page, click the kebab menu on the newly created cadence and select Add iteration.

   

5. Fill out the form and click Create iteration.

6. On the iteration report page, you should be able to see the kebab menu on the top right, which is migrated now to use new dropdown.

7. The kebab menu should contain both Edit and Delete items.

Creating an automatic iteration

1. Go to a group. In the left navigation, click on Plan > Iterations.
2. There should already be some iteration cadences created.
3. Pick an iteration cadence that already has some iterations, and click on an iteration from the list.
4. On the iteration report page, you should be able to see the kebab menu on the top right, which is migrated now to use new dropdown.
5. The kebab menu should contain only Edit option, and not Delete.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #418063 (closed)