[refactor]: Improve decoding of `ChainId`

[Erigara]

          This could be improved by using constructor `fn new(inner: impl Into<Box<str>>)`.

I will extract it into separate good first issue.

Originally posted by @Erigara in #4185 (comment)

Idea is to remove redundant clone by directly convert from String to Box<str>.

[mversic]

remove custom Decode implementation for ChainId after this PR is merged

[Erigara]

@mversic oh it will be much better solution