Standardize LSN formatting by zero padding

 Standardize LSN formatting by zero padding
 
 This commit standardizes the output format for LSNs to ensure consistent
 representation across various tools and messages.  Previously, LSNs were
 inconsistently printed as `%X/%X` in some contexts, while others used
 zero-padding.  This often led to confusion when comparing.
 
 To address this, the LSN format is now uniformly set to `%X/%08X`,
 ensuring the lower 32-bit part is always zero-padded to eight
 hexadecimal digits.
 
 Author: Japin Li <japinli@hotmail.com>
 Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com>
 Reviewed-by: Álvaro Herrera <alvherre@kurilemu.de>
 Discussion: https://postgr.es/m/ME0P300MB0445CA53CA0E4B8C1879AF84B641A@ME0P300MB0445.AUSP300.PROD.OUTLOOK.COM