[FIX] website: prevent carousel indicators errors

In this commit [1] (merged in 16.0) a bugfix has been made in the
`removeSlide` function but this one should have been applied on all
supported versions because the bug it fixes is present on all versions.
The bug it fixes is the following:
- Drop a carousel block on a page
- Remove the *first* slide

=> There is no active indicator.

Moreover, the bugfix made in 16.0 [1] introduces another error: when a
slide is removed from the carousel the indicators are not in a correct
state anymore.

Following the same steps with the changes of [1]:
- Drop a carousel block on a page
- Remove a slide

=> Indicators are no longer consistent with the slides so tracebacks
appear during the carousel slides. The list of indicators must have on
each element a `data-slide-to` attribute which must reflect the
position of the slide (starting with 0).

So this commit is to backport the fix from 16.0 [1] to 14.0 and to fix
the new bug that [1] introduces.

[1]: https://github.com/odoo/odoo/commit/f7055d3dbabfbe471f490bd65c2032f5251f3f37



task-3040931
opw-3051615

closes odoo/odoo#106611

X-original-commit: 16405934
Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>