Make the generator always generate legacy and multi path templates

[sofisl]

Context: googleapis/google-cloud-node#5289

There is a known breaking change in the generator that when an API specifies multiple pattern types, after only having one, the generator only generates paths for the new ones, and not the old ones.

A possible fix is to always generate the legacy naming, even if new patterns are introduced. So, in this example, we'd always generate secretVersionPathTemplate and the new multipattern ones too.

This is where the paths get rendered:

gapic-generator-typescript/templates/cjs/typescript_gapic/src/$version/$service_client.ts.njk

Line 1008 in 7cfda61

{{ id.get(template.name.toCamelCase() + "Path") }}(

And the logic is actually set here:

gapic-generator-typescript/typescript/src/schema/resource-database.ts

Line 68 in 7cfda61

const multiPattern = patterns!.length > 1;

We'd need to make sure both branches are executed, i.e., regardless of whether there are multipatterns, we should also generate a legacy pattern as well.