Model registry: Increase Description text limits

What does this MR do and why?

This MR adds a text limit to the field description in both Ml::Model and Ml::ModelVersion.

Migration up

bin/rails db:migrate:up:main VERSION=20240824101146
main: == [advisory_lock_connection] object_id: 127380, pg_backend_pid: 92494
main: == 20240824101146 AddTextLimitModelDescription: migrating =====================
main: -- transaction_open?(nil)
main:    -> 0.0000s
main: -- transaction_open?(nil)
main:    -> 0.0000s
main: -- execute("ALTER TABLE ml_models\nADD CONSTRAINT check_d0c47d63b5\nCHECK ( char_length(description) <= 10000 )\nNOT VALID;\n")
main:    -> 0.0012s
main: -- execute("SET statement_timeout TO 0")
main:    -> 0.0005s
main: -- execute("ALTER TABLE ml_models VALIDATE CONSTRAINT check_d0c47d63b5;")
main:    -> 0.0010s
main: -- execute("RESET statement_timeout")
main:    -> 0.0005s
main: -- transaction_open?(nil)
main:    -> 0.0000s
main: -- transaction_open?(nil)
main:    -> 0.0000s
main: -- execute("ALTER TABLE ml_model_versions\nADD CONSTRAINT check_caff7d000b\nCHECK ( char_length(description) <= 10000 )\nNOT VALID;\n")
main:    -> 0.0005s
main: -- execute("ALTER TABLE ml_model_versions VALIDATE CONSTRAINT check_caff7d000b;")
main:    -> 0.0011s
main: == 20240824101146 AddTextLimitModelDescription: migrated (0.0422s) ============

main: == [advisory_lock_connection] object_id: 127380, pg_backend_pid: 92494

Migration down

bin/rails db:migrate:down:main VERSION=20240824101146
main: == [advisory_lock_connection] object_id: 127380, pg_backend_pid: 91543
main: == 20240824101146 AddTextLimitModelDescription: reverting =====================
main: -- transaction_open?(nil)
main:    -> 0.0000s
main: -- transaction_open?(nil)
main:    -> 0.0000s
main: -- execute("            ALTER TABLE ml_models\n            DROP CONSTRAINT IF EXISTS check_d0c47d63b5\n")
main:    -> 0.0010s
main: -- transaction_open?(nil)
main:    -> 0.0000s
main: -- transaction_open?(nil)
main:    -> 0.0000s
main: -- execute("            ALTER TABLE ml_model_versions\n            DROP CONSTRAINT IF EXISTS check_caff7d000b\n")
main:    -> 0.0007s
main: == 20240824101146 AddTextLimitModelDescription: reverted (0.0206s) ============

main: == [advisory_lock_connection] object_id: 127380, pg_backend_pid: 91543

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Before	After

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Related to #480525 (closed)