Remove traces of gl-datepicker-input in CSS files

What does this MR do and why?

Commit 1: Remove CSS class in HTML without styles

No styles were attaches to this CSS class:

Commit 2: Remove daterange-container from CSS

Could not find an HTML element for this CSS class:

Commit 3: Remove unused cycle analytics CSS

I believe this code is not needed anymore in the cycle analytics (now called Value Stream Analytics)

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

How to set up and validate locally

ee/app/assets/javascripts/iterations/components/iteration_cadence_form.vue

1. Ensure to enable the iteration cadences FF (it's enabled by default.)

   Feature.enable(:iteration_cadences)

2. Visit any group (not project.) Via the left menu bar, navigate to the Iterations and click New iterations cadence, or go to Go to http://gdk.test:3000/groups/twitter/-/cadences/new (or any other group)

Related to #479771 (closed)