fix(ui5-date-picker): Fix background vs foreground width mismatch.

[sap-lh]

Hi colleagues,

While updating our UI5 version, I noticed that some elements got 'glitched' out, and it's more apparent on dark mode.

I can verify that adding back the width:100% property that was removed in 89ccfb8 resolves the issue. Notice that this property is still present in the DateTimePicker. It seems that its removal was not related entirely to the rest of the commit.

Before

After

HTML description

1. The ui5-date-picker has a full-wifth and background-color: var(--sapField_Background); property.
2. Its shadow-root child (ui5-datetime-input) does not have a width:100% property anymore, so that this background is larger than the child element it is trying to cover.

Regarding DTO, I work at SAP, but I will end the commit message with a sign-off regardless.

Thank you for your amazing work.

Thank you for your contribution! 👏

PR checklist

• Check the Development Hints

• Follow the Commit message Guidelines

For example: fix(ui5-*): correct/fix sth or feat(ui5-*): add/introduce sth. If you don't want the change to be part of the release changelog - use chore, refactor or docs.

• Add proper description about the background of the change and the change itself

• Link to an existing issue (if available)

Use Fixes: {#PR_NUMBER} to close the issue automatically when the PR is merged
or Related to: {#PR_NUMBER} to just create a link between the PR and the issue.

• Read the Contributing Guidelines

[cla-assistant]

All committers have signed the CLA.

[cla-assistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}