Seven Texas businessmen have been indicted for allegedly conspiring to inflate the value of Texas real estate to fraudulently obtain more than $100 million from five thrift institutions, the Justice Department announced. Four of the five S&Ls involved in the alleged fraud scheme have gone out of business, the department said. Among those charged were Spencer H. Blain Jr., chairman of the board of Empire Savings & Loan Assn. in Mesquite, Tex., and Paul Arlin Jensen, 38, chairman of Lancaster First Federal Savings & Loan Assn. of Lancaster, Tex. Three real estate promoters and developers along with two land appraisers for the S&Ls also were indicted. Blain and Jensen were also were charged with racketeering.