old chain: R3 / ISRG Root X1
new chain: E1 / ISRG Root X2
No user interaction or migration is required for existing installations
as we install 'E1' and 'ISRG Root X2' for some time already.
Let's Encrypt planned the transition to ISRG's root certificate ("ISRG Root
X1") on July 8, 2019, but postponed several times.
Finally they found another solution: A certificate 'ISRG Root X1', but
cross-signed with 'DST Root CA X3' and with a livetime that exceeds that
of the root CA. This is said to work for most operating system where root
certificate authorities are just 'trust anchors'.
I doubt this is true for RouterOS, where certificates are just imported
into the certificate store. So let's migrate to 'ISRG Root X1' now.
Using 'print count-only' always prints a number to terminal, even if the
value is evaluated in a condition or assigned to a variable. This can be
quite annoying. Behavior will not chance (SUP-25503), so replacing the
code...
