Fix code scanning alert no. 2: Incorrect conversion between integer types

[amold1]

Fixes https://github.com/linode/linode-blockstorage-csi-driver/security/code-scanning/2

To fix the problem, we need to ensure that the conversion from int64 to int is safe by checking that the value of startingPage is within the bounds of the int type. This can be done by adding a bounds check before the conversion. If the value is out of bounds, we should handle the error appropriately.

1. Add bounds checking for startingPage before converting it to int.
2. Use the constants math.MaxInt and math.MinInt to check the bounds.
3. If startingPage is out of bounds, return an error.

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