Remove fix for client info having display sizes

[Nexarian]

During the discussion of #212, which was prompted by neutrinolabs/xrdp#1895, a request was made to make xorgxrdp be backwards compatible with the change to xrdp_client_info.h

This backwards compatibility is awkward and not something we normally support, but we're doing it this one time. Remove the
#if CLIENT_INFO_CURRENT_VERSION == 20210723 blocks.

[metalefty]

I'm thinking of create a branch to manage compatibility between xrdp and xorgxrdp.

I'll create v0.9 branch in xorgxrdp, that is compatible with xrdp v0.9. The reason why the branch is v0.9 rather than v0.2 is to sync version with xrdp not to confuse. xorgxrdp v0.9 is compatible with xrdp v0.9. It's simple, isn't it?

I don't intend to make any changes to past releases. So the version of xorgxrdp will jump from v0.2.18 to v0.9.19.

[metalefty]

I raised #221 in order to commit compatibility for some customers.