Testing different configuration for running ERA5 experiments (Draft PR not to be merged)

[ankitpatnala]

Description

This is a dummy PR to keep track of the workable configuration for training on ERA5.

• config/default_config.yml
• forecasting_finetuning_config.yml ( overwrite over default config for finetuning forecast experiments)
• config/streams/streams_anemoi/era5.yml

Issue Number #382

The motivation behind this PR to keep track on the config that is working for all the collaborators across different HPCs

[FussyDuck]

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