refactor: Replace unused exception parameter with underscore

[devch37]

Description

Summary of the change: Provide a concise summary of this PR. Describe the changes made in a single sentence or short paragraph

Replace unused exception parameter in catch block.
(exposed-core/src/main/kotlin/org/jetbrains/exposed/v1/core/vendors/OracleDialect.kt)
(exposed-jdbc/src/main/kotlin/org/jetbrains/exposed/v1/jdbc/statements/InsertBlockingExecutable.kt)
(exposed-jdbc/src/main/kotlin/org/jetbrains/exposed/v1/jdbc/transactions/Transactions.kt)
(exposed-r2dbc/src/main/kotlin/org/jetbrains/exposed/v1/r2dbc/transactions/Transactions.kt)

Detailed description:

• Why: Explain the reasons behind the changes. Why were they necessary?
  Following Kotlin's idiomatic conventions, unused variables should be represented with an underscore (_) rather than named parameters. This improves code readability and makes it immediately clear that the exception parameter is intentionally unused. It also eliminates IDE warnings about unused variables and aligns with the Kotlin style guide recommendations.

• What: Detail what changes have been made in the PR.
  This PR replaces unused exception parameters in catch blocks with underscore notation across the codebase. The changes affect exception handling where the caught exception is not referenced in the catch block body.

• How: Describe how the changes were implemented, including any key aspects of the code modified or new features added.

1. Identified all catch blocks where exception parameters are declared but never used
2. Replaced named exception parameters (e.g., e, ex, exception) with _
3. Maintained the exception type specification for proper exception handling
4. No functional changes were made; this is purely a style improvement

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Type of Change

Please mark the relevant options with an "X":

• Bug fix
• New feature
• Documentation update

Updates/remove existing public API methods:

• Is breaking change

Affected databases:

• MariaDB
• Mysql5
• Mysql8
• Oracle
• Postgres
• SqlServer
• H2
• SQLite

Checklist

• Unit tests are in place
• The build is green (including the Detekt check)
• All public methods affected by my PR has up to date API docs
• Documentation for my change is up to date

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Related Issues

[bog-walk]

Thanks for starting this @devch37

Could you please address the comments and also take a look at a similar catch block in OracleDialect.kt from exposed-core? It seems to be the only case missing from your changes.

[bog-walk]

Thanks @devch37 and apologies for the delay. There was an unrelated CI issue we wanted to resolve before any new merges.