fix(spanner): fix escaping of database name in spanner ddl with POSTGRES dialect

[rahul2393]

Currently name attribute having - in value cannot be populated because of issue in escaping database name
e.g

variables "database_name" {
type = string
default = "dbatest5-postgres"
}

resource "google_spanner_database" "database" {
instance = google_spanner_instance.main.name
name = ""${var.database_name}""
database_dialect = "POSTGRESQL"
deletion_protection = false
}

This PR will fix the escaping with POSTGRES dialect

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Release Note Template for Downstream PRs (will be copied)

spanner: fix escaping of database names with Postgres dialect in `google_spanner_database`

[modular-magician]

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• REPLACEME

Please only use the types listed in https://github.com/GoogleCloudPlatform/magic-modules/blob/master/.ci/RELEASE_NOTES_GUIDE.md.

[modular-magician]

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[modular-magician]

Oops! It looks like you're using an unknown release-note type in your changelog entries:

• REPLACEME

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[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 2 files changed, 3 insertions(+), 3 deletions(-))
Terraform Beta: Diff ( 2 files changed, 3 insertions(+), 3 deletions(-))
TF Validator: Diff ( 3 files changed, 4 insertions(+), 4 deletions(-))

[modular-magician]

Tests analytics

Total tests: 1982
Passed tests 1741
Skipped tests: 240
Failed tests: 1

Action taken

Triggering VCR tests in RECORDING mode for the following tests that failed during VCR: TestAccSpannerDatabase_postgres

[modular-magician]

Tests passed during RECORDING mode:
TestAccSpannerDatabase_postgres[view]

All tests passed
View the build log or the debug log for each test

[shuyama1]

Thank you!