remove unneeded divergence from Canton sources

[stephencompall-DA]

For DACH-NY/canton#32877, part of #546, there were aspects of CantonConfig/Environment usage where the upstreaming would be far nicer, or in some cases could only be upstream-compatible, with a different approach to our own divergence. So those changes are collected here.

• remove SharedCantonConfig#name
• move Environment#createConsole back where it was
• restore SharedCantonConfig#mergeDynamicChanges
  • restore Environment#pokeOrUpdateConfig
• some statically empty Maps
• override startupConfigFileMonitoring to disable instead of just deleting from the fork
• remove unused environmentFactory addition, which is accessible elsewhere
• restore TestEnvironment#actualConfig's original implementation
• use Base* pattern for some generalized classes with type aliases to avoid many, many downstream renames in Canton test code
• drop unneeded tparam from Runner

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Cluster Testing

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