Because of the deprecated functions removals in these PR:

• Remove deprecated pgr analyze graph v4.0 #2838
• Remove deprecated pgr analyze one way v4.0 #2839
• Remove deprecated pgr create vertices table v4.0 #2841
• remove deprecated pgr create toplogy v4.0 #2842
  And the rewrite done on
• Port rewrite pgr node network v4.0 #2859

The following internal functions are not used anymore and can be removed:

• _pgr_checkverttab(text,text[],integer,text)
• _pgr_createindex(text,text,text,integer,text)
• _pgr_createindex(text,text,text,text,integer,text)
• _pgr_endpoint(geometry)
• _pgr_getcolumnname(text,text,integer,text)
• _pgr_getcolumnname(text,text,text,integer,text)
• _pgr_getcolumntype(text,text,integer,text)
• _pgr_getcolumntype(text,text,text,integer,text)
• _pgr_gettablename(text,integer,text)
• _pgr_iscolumnindexed(text,text,integer,text)
• _pgr_iscolumnindexed(text,text,text,integer,text)
• _pgr_iscolumnintable(text,text)
• _pgr_msg(integer,text,text)
• _pgr_onerror(boolean,integer,text,text,text,text)
• _pgr_pointtoid(geometry,double precision,text,integer)
• _pgr_quote_ident(text)
• _pgr_startpoint(geometry)
• _pgr_versionless(text,text)

Function _pgr_get_statement is to be placed on its own file.