chore: restore sass deprecation warning silencing

[jcfranco]

Related Issue: N/A

Summary

Restores deprecated warnings prematurely removed in https://github.com/Esri/calcite-design-system/pull/12465/files#diff-50e581eb0e72b23e2222ae7118aad3c0a006d398318cb468fef90c04be473012L77-L82.

Also addresses a new mixed-decls warning introduced in #12516:

@esri/calcite-components:build: Deprecation Warning [mixed-decls]: Sass's behavior for declarations that appear after nested
@esri/calcite-components:build: rules will be changing to match the behavior specified by CSS in an upcoming
@esri/calcite-components:build: version. To keep the existing behavior, move the declaration above the nested
@esri/calcite-components:build: rule. To opt into the new behavior, wrap the declaration in & {}.
@esri/calcite-components:build:
@esri/calcite-components:build: More info: https://sass-lang.com/d/mixed-decls
@esri/calcite-components:build:
@esri/calcite-components:build: ┌──> ../../../../packages/calcite-components/src/components/popover/popover.scss
@esri/calcite-components:build: 22 │ max-inline-size: var(--calcite-popover-max-size-x, 100vw);
@esri/calcite-components:build: │ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ declaration
@esri/calcite-components:build: ╵
@esri/calcite-components:build: ┌──> ../../../../packages/calcite-components/src/assets/styles/_floating-ui.scss
@esri/calcite-components:build: 94 │ ┌ @starting-style {
@esri/calcite-components:build: 95 │ │ opacity: 0;
@esri/calcite-components:build: 96 │ │ inset-block-start: 0;
@esri/calcite-components:build: 97 │ │ /* stylelint-disable-next-line liberty/use-logical-spec -- explicit position */
@esri/calcite-components:build: 98 │ │ left: 0;
@esri/calcite-components:build: 99 │ │ }
@esri/calcite-components:build: │ └─── nested rule
@esri/calcite-components:build: ╵
@esri/calcite-components:build: ../../../../packages/calcite-components/src/components/popover/popover.scss 22:3 root stylesheet

Note: deprecation silencing will be removed in https://github.com/Esri/calcite-design-system/pull/12216/files#diff-50e581eb0e72b23e2222ae7118aad3c0a006d398318cb468fef90c04be473012.

[jcfranco]

@driskull I opted into the new behavior to address the warning (produces separate selector), but we should look into updating some mixins to allow some CSS props overrides.

[driskull]

👍