lang: Remove unused code related to deprecated program id macros

[acheroncrypto]

Problem

rustc 1.82.0-nightly prints some warnings related to unused code:

   Compiling anchor-attribute-account v0.30.1 (/home/x/anchor/lang/attribute/account)
warning: function `deprecated_id_to_tokens` is never used
  --> /home/x/anchor/lang/attribute/account/src/id.rs:75:4
   |
75 | fn deprecated_id_to_tokens(
   |    ^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: `#[warn(dead_code)]` on by default

warning: struct `IdDeprecated` is never constructed
   --> /home/x/anchor/lang/attribute/account/src/id.rs:146:8
    |
146 | struct IdDeprecated(proc_macro2::TokenStream);
    |        ^^^^^^^^^^^^

warning: struct `ProgramSdkId` is never constructed
   --> /home/x/anchor/lang/attribute/account/src/id.rs:168:8
    |
168 | struct ProgramSdkId(proc_macro2::TokenStream);
    |        ^^^^^^^^^^^^

warning: struct `ProgramSdkIdDeprecated` is never constructed
   --> /home/x/anchor/lang/attribute/account/src/id.rs:189:8
    |
189 | struct ProgramSdkIdDeprecated(proc_macro2::TokenStream);
    |        ^^^^^^^^^^^^^^^^^^^^^^

warning: struct `Pubkeys` is never constructed
   --> /home/x/anchor/lang/attribute/account/src/id.rs:258:8
    |
258 | struct Pubkeys {
    |        ^^^^^^^

warning: `anchor-attribute-account` (lib) generated 5 warnings

Summary of changes

Remove unused code related to the deprecated program id macros.

This is not a breaking change since all of the removed code was private.

[vercel]

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