Fix SyncProductFilter and SyncCAFilter having no effect

[Pichatorn-A4K]

Two independent problems in the sync-filter area, both of which make a configured filter silently do
something other than what it says. Found while auditing the shipped 2.4.1 assembly; both are also
present in 2.4.2-rc.0.

1. SyncProductFilter never filters

GetAllConnectorCertsForOrder has three filter blocks in a row. The SyncCAFilter and Division
blocks both return null when the order does not match; the product block logs and then falls
through:

if (productIds != null && productIds.Count > 0 && !productIds.Contains(orderResponse.product.name_id.ToString()))
{
    _logger.LogTrace($"Found order ID {orderId} that does not match Product filter. ... Skipping...");
}   // <- no return, so the order is synchronized anyway

It appears to work on a full sync only because ListAllCertificateOrders also sends
filters[product_name_id] to DigiCert. On an incremental sync the filter is not applied at all,
because status-changes takes no product filter — so out-of-scope products reach Command while the
log claims they were skipped.

2. SyncCAFilter never matches a lower-case value

caList.ForEach(c => c.ToUpper());

String.ToUpper() returns a new string; the result is discarded, so the list is never upper-cased.
The comparison downstream is:

!caFilterIds.Contains(orderResponse.certificate.ca_cert.Id.ToUpper())

The DigiCert side is upper-cased, so a CA ID entered in lower case matches nothing and every
order is skipped — the sync returns zero certificates with no error, only a trace line per order.

CertCentralConfig.SyncCAs also materialises a fresh List<string> on each access, so an in-place
mutation could not have persisted even if ToUpper() had mutated. The fix assigns the projection
back, and additionally trims and drops empty entries so a trailing comma in the config value does not
produce an entry that can never match.

Verification

Driving Synchronize() offline against a fake CertCentralClient:

• a lower-case SyncCAFilter matches the order (and a genuinely different filter value still
  excludes it, so the test cannot pass for the wrong reason);
• SyncProductFilter excludes a non-matching product and keeps a matching one.

Reverting either change makes the corresponding test fail. The tests are not in this PR because the
repository has no test project; happy to contribute the harness separately.

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