fa1436c42 [qa] util: Remove unused sync_chain (MarcoFalke)
Pull request description:
The util function `sync_blocks` already checks for equal chains, so we can remove the unused `sync_chain`.
Also cleaned up the errors that are printed in case of timeout:
```
AssertionError: Block sync timed out:
'72a3a3e9dcfd0a09204c3447af0f481d19641eeadbe6a91b8e680ed614bc7712'
'5032af4ae22ae7a21afdc9d9f516877309c4dd8ef2ecadb9354be7088439b4a6'
'5032af4ae22ae7a21afdc9d9f516877309c4dd8ef2ecadb9354be7088439b4a6'
```
and
```
AssertionError: Mempool sync timed out:
{'c2af943d9b321c36e0f5a153a9d3d8b11bdd46ceb28e38f5fd2c722e3edb3563'}
set()
set()
```
Tree-SHA512: cb4ad30e3e3773072f59afa2c81cfa27bd8f389a93f02acb919990298627fcfbaa53a3d3944d827cc8a5d009871e42a47ea09e9bb93e85c22e3af6a24a574e5d
0f0229d0c3