Optimize secp256k1_fe_normalize_weak calls.

Summary:
Move secp256k1_fe_normalize_weak calls out of ECMULT_TABLE_GET_GE and ECMULT_TABLE_GET_GE_STORAGE and into secp256k1_ge_globalz_set_table_gej instead.

This is a backport of secp256k1's PR550

Test Plan:

ninja check-secp256k1

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D4974