PKM and colorectal carcinoma: Univariable and multivariable‐adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between the expression levels (low, moderate, and high) of individual Warburg‐related proteins (LDHA, GLUT1, MCT4, PKM2, p53, and PTEN), and CRC‐specific and overall survival