[6.x] Remove z-index from replicator. I think the z-2 class is unnecessar…

[jaygeorge]

Description of the Problem

As per #14105 under certain circumstances, replicators can appear above sticky Bard toolbars (a Bard field with another Bard field inside, with a replicator set).

What this PR Does

• This removes the z-index value from replicators.
  • z-2 was added during the very initial draft of v6, likely as a safety value(?), and I don't think it needs to be there. Therefore, I think it's safe to remove it.
• Closes Bard toolbar behind replicator inside sets #14105

Before

After

How to Reproduce

1. Add a Bard field with another Bard field inside, with a replicator set
2. Scroll downwards so the sticky toolbar rolls over the replicator set, where you can see the replicator appears above it.

[AtmoFX]

Hey @jaygeorge

Though I did not provide a screenshot for it, I did say the replicator's + Add block button has the exact same z-2 and the exact same issue as the set.
I made a quick search and believe it should be cleaned here:

cms/resources/js/components/fieldtypes/replicator/AddSetButton.vue

Line 7 in 19256b5

<Button v-if="enabled" size="sm" :text="label" icon="plus" class="relative z-2" />

If that is the correct place, I'd like to say the + Add Block button already gets the relative class from (I suppose)

cms/resources/js/components/ui/Button/Button.vue

Line 51 in 19256b5

base: 'relative inline-flex items-center justify-center whitespace-nowrap shrink-0 font-medium antialiased cursor-pointer no-underline disabled:text-gray-400 dark:disabled:text-gray-600 disabled:[&_svg]:opacity-30 disabled:cursor-not-allowed [&_svg]:shrink-0 [&_svg]:text-gray-925 [&_svg]:opacity-60 dark:[&_svg]:text-white',

so it could be dropped too.