Default HTTP2 header size decreased, breaking oauth.

[t-8ch]

In #376/#392 http2_max_field_size has been made configurable.
This changed the default from 4K to 1K breaking our oauth Bearer token header.

For client_header_buffer_size a small size is enough, as larger buffers are used if necessary.
For http2_max_field_size no larger buffers are allocated.

So I think it would be better to use the $cfg.LargeClientHeaderBuffers size for http2_max_field_size

(And http2_max_field_size is for the compressed key-value pair. For the decompressed header there is http2_max_header_size)

[aledbf]

@t-8ch apologies for the error. As I said in #376 we tried to use the same value which from your report is not the right approach. I will ad a new config HTTP2MaxFieldSize.

[t-8ch]

@aledbf No reason to apologise :-)
Thanks for the quick fix!