FE: Topics: Do not send properties which are not defined explicitly

[p-eye]

• Breaking change? (if so, please describe the impact and migration path for existing application instances)

What changes did you make? (Give an overview)
although retention.bytes is from "Custom Parameter" when creating topic, it was declared directly in Form and Configs.
so the default value for retention.bytes didn't work.
after removed, retention.bytes works like other Custom Parameters.
Fixes #4030

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[Haarolean]

@p-eye thank you for the contribution. What about other params tho?

[sonarqubecloud]

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[p-eye]

@Haarolean
because retention.bytes is one element of customParams, it didn't have to be declared.
but other params are not included in customParams list.
so when they are removed from the code, my explicit config values are not passed to backend. therefore i fixed only for retention.bytes.

thank you for your inspection