Chip - remove pf-m-read-only from isReadOnly variant

[mcoker]

For reference, the core PR: patternfly/patternfly#2941

The .pf-m-read-only class was only for styling in core, and it's no longer needed as you can simply remove the close button. So we can remove that class from being applied when isReadOnly is true, and just show the close button.

Looks like the isReadOnly && styles.modifiers.readOnly bit in these lines

patternfly-react/packages/react-core/src/components/ChipGroup/Chip.tsx

Line 104 in 43348f2

className={css(styles.chip, isReadOnly && styles.modifiers.readOnly, className)}

patternfly-react/packages/react-core/src/components/ChipGroup/Chip.tsx

Line 81 in 43348f2

className={css(styles.chip, isReadOnly && styles.modifiers.readOnly, className)}

[evwilkin]

Looks to be resolved by #4116