[8.x] Fix runway search on models with individual connections

[godismyjudge95]

We recently ran into an issue where the search on our Runway models was not working properly (as in it wasn't filtering at all): https://discord.com/channels/489818810157891584/1151898550305837086/1415710334219583518

After a bit of digging, I found out that it is because we are using the Orbit Eloquent driver for the model, and Orbit specifies the DB connection on a per model basis. This means that when this code is called for scoping the Runway search:

    public function scopeRunwaySearch(Builder $query, string $searchQuery)
    {
        $this->runwayResource()->blueprint()->fields()->all()
            ->filter(fn (Field $field) => Schema::hasColumn($this->getTable(), $field->handle()))
            ->reject(fn (Field $field) => $field->visibility() === 'computed')
            ->each(fn (Field $field) => $query->orWhere($this->getColumnForField($field->handle()), 'LIKE', '%'.$searchQuery.'%'));
    }

it gets the default DB connection and not the Orbit connection.

This is not an Orbit specific issue as this behavior would happen with any model that specifies a different DB connection than the default.

This PR adds a failing test and a simple fix to use the model's connection and subsequently schema builder to check for the columns' existence.

[godismyjudge95]

Failing tests appear to be Github actions having issues again... 🫠
Implemented your suggestions.

[duncanmcclean]

Looks good, thanks!

[github-actions]

Released as part of v8.8.3.