[confighttp/configgrps] Rename the fields of types that were renamed in configtls

[arjunmahishi]

          We should at least open a PR about re-naming the variable as well.

Originally posted by @bogdandrutu in #9495 (comment)

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As a part of #9495, some types in configtls were renamed to match the naming convention followed in other packages. But the fields/attributes that use those types were not renamed to maintain backward compatibility. Opening this PR to track that change.

Types that were renamed

• TLSClientSetting to ClientConfig
• TLSServerSetting to ServerConfig
• TLSSetting to Config

These types are used with some struct attributes in the package confighttp and configgrpc.